System to measure density, specific gravity, and flow rate of fluids, meter, and related methods

ABSTRACT

A system to measure fluid flow characteristics in a pipeline, meter, and methods includes a pipeline having a passageway to transport flowing fluid therethrough, a process density meter including at least portions thereof positioned within the pipeline to provide flowing fluid characteristics including volumetric flow rate, fluid density, and mass flow rate of the flowing fluid, and a fluid characteristic display to display the fluid characteristics. The process density meter includes a vortex-shedding body positioned within the pipeline to form vortices and a vortex meter having a vortex frequency sensor to measure the frequency of the vortices and to determine the volumetric flow rate. The process density meter further includes a differential pressure meter positioned adjacent the vortex-shedding body to produce a differential pressure meter flow rate signal indicative of the density of fluid when flowing through the pipeline. The process density meter also includes a thermal flow meter positioned adjacent the vortex-shedding body to produce a mass flow rate signal indicative of the mass flow rate of fluid when flowing through the pipeline. The process density meter produces an output of a volumetric flow rate, a flowing fluid density, and a mass flow rate to be displayed by the fluid characteristic display.

RELATED APPLICATIONS

This application claims the benefit of provisional patent applicationNo. 60/495,743, filed on Aug. 15, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to flow meters. In more specificaspects, the present invention relates to the measurement of thedensity, specific gravity, and flow rate of flowing fluids, systems,apparatus and methods.

2. Description of the Related Art

Many industrial facilities feed fuel gases to their industrialcombustion processes. Particularly, these fuel gases tend to be lowmolecular weight hydrocarbon fuel gases. These fuel gases typically havea constantly changing hydrocarbon composition. To maintain an efficientfuel-air ratio combustion control, the hydrocarbon density, directlyrelated to specific gravity, and thus, the BTU content, must be known.Density measurement techniques are typically expensive and complex. Mostindustrial combustion processes with varying composition fuel gases useeither gas chromatographs or vibrating spool densitometers to determinefuel gas density. However, both of these densitometers, though veryaccurate, are very costly and require highly skilled technicians toconduct frequent maintenance.

The typical gas chromatographs can provide 0.1% accuracy but are verycomplex. For example, the Yamatake Model HGC303 Heat Value GasChromatograph manufactured by Yamatake Corporation, located inShibuya-ku, Tokyo, uses a gas chromatography measuring principle tomeasure heat value of natural gas and is used generally for the purposeof natural gas consumption management. A heated filament is contained ina stainless steel block of the detector. The individual components ofthe gas sample are separated in chromatograph columns and passed througha detector. Each component of the gas that passes through the detectortransfers heat from the measuring thermistor to the wall of the block.The amount of heat transferred is dependent on the concentration andthermal conductivity of the gas component. The resistance of themeasuring thermistor changes relative to the reference thermistor. Thischange is converted to a voltage.

A vibrating spool densitometer can also theoretically obtain a statedaccuracy as high as 0.1%. They require, however, specialized samplingand discharge arrangements. For example, the Solartron B1253manufactured by Solartron Mobrey Limited, located in Slough BerksEngland, is a gas density meter whose measuring principle is based onthe use of a resonating cylinder. The pipeline containing the gas istapped to extract a continuous gas sample to be passed through a densitytransducer. The density of the gas flowing through a transducer changesthe natural resident frequency of the cylinder. By maintaining thisvibration and measuring its frequency electronically, the density of thegas which is directly related to mass flow can be determined.

Flame BTU analyzers can give between 0.4-2.0% accuracy but are also verycomplex. For example, the COSA 9600 manufactured by COSA Instrumentlocated in Norwood N.J. is a flame BTU analyzer whose measuringprinciple, typically called the “residual oxygen measurement method,” isbased on the analysis of the oxygen content of a sample of fuel gasafter combustion. A continuous sample of gas is mixed with dry air at aprecise ratio selected dependent upon the BTU range of the gas to bemeasured. The fuel-air mixture is oxidized in a combustion furnace inthe presence of a catalyst at 800° C., and an oxygen concentration ofthe combustion sample is measured by a zirconia oxide cell. The residualoxygen provides a measurement of the combustion air requirement of thesample gas.

Coriolis meters can be nearly as accurate while being somewhat lesscomplex for certain types of fuel gases. The measurement of the massflow rate in a Coriolis meter is based on the principle of causing amedium to flow through a flow tube inserted in the pipe and vibratingduring operation, whereby the medium is subjected to Coriolis forces.The latter causes the inlet-side and outlet-side portions of the flowtube to vibrate out of phase with respect to each other. The magnitudeof these phase differences is a measure of the mass flow rate. Thevibrations of the flow tube are therefore sensed by use of two vibrationsensors positioned at a given distance from each other along the flowtube and converted by these sensors into measurement signals having aphase difference from which the mass flow rate is derived. The meters,however, typically cannot accurately measure low molecular weight gasdensity.

There is a need to easily and without an excessively complex instrumentmeasure density and flow rate of low molecular weight fuel gases fed tocombustion boilers. Vortex Shedding Flow Meters are fairly simpleinstruments requiring little maintenance. Fluid passing around a bluffbody produces a stream of vortices with a generation rate which isproportional to the flow rate of the fluid. A sensor responsive to thevortices produces a signal having a frequency representing the flowrate. The flow rate signal can then be used for calculating theresulting volumetric flow rate of the fluid in the pipe. The measure offluid flow rate for the Vortex Shedding Flow Meter, however, isindependent of density. Thus, it is not possible to derive density ormass flow rate from the volumetric flow rate measurement, alone,especially where the fluid is in a gaseous form. An Averaging Pitot Tubeand a Thermal Flow Meter, however, both measure flow rate dependent uponfluid density.

Various devices trying to apply this principle have been proposed. Forexample, U.S. Pat. No. 4,523,477, by Miller, titled “Planar-MeasuringVortex-Shedding Mass Flow Meter” describes placing up to two dynamicpressure ports of a differential pressure measuring device at theupstream surface of the vortex-shedding body and placing a staticpressure port along the circumference of the production pipe housing thevortex meter in a position traverse to the fluid flow and withinone-half of the vortex wavelength of the dynamic pressure port. Thedynamic pressure port passageways extend through the production pipe andare coupled via a manifold connector on the external surface of theproduction pipe. A divider circuit divides the electrical signal of thedifferential pressure measuring device by a flow rate signal obtainedfrom the velocity sensing portion of the device to obtain mass flow.Because it requires breaching the production pipe for each of the staticand dynamic ports of the differential pressure measuring device,however, the device, is complex to install. Additionally, it is notsufficiently accurate because it does not directly provide pressure andtemperature compensated density.

Also, for example, in GB 2,212,277A, by Jackson et al., titled “Gas FlowMeter,” the meter calculates gas density in order to compute the valuesfor mass flow. The gas density, however, is not continuously measuredthrough all flow ranges but is instead computed based on charted data.The thermal flow meter portion, separate from the vortex flow meterportion, only measures mass flow at low flow rates and the vortex meterportion only measures velocity at high flow rates with an overlap regionin which the outputs of the two portions of the device are combined toprovide a calculated gas density to determine mass flow rate for thehigh flow rates. Temperature is monitored and can sometimes be appliedto attempt to correct the calculated gas density during an interim wherethe flow velocity is outside the overlap region, and thus, unable toprovide for a truly updated gas density calculation. The device does nothave a combined unit that measures fluid density at substantially alloperational flow rates, and therefore cannot provide for a continuouslyupdated gas density much less a continuously updated gas density output.Also, the device is truly two separate devices as the separate thermalflow meter is positioned in a separate meter passage than that of thevortex flow meter and is thus more difficult and complex to install.

Accordingly, the Applicant has recognized that there still exists a needfor a simple, no-moving-part, and low-cost industrial meteringinstrument capable of measuring and outputting process fluid density aswell as flow rate. Applicant has especially recognized the need for anintegrated metering instrument accurate for measuring low molecularweight fuel gases fed to combustion process. Applicant also recognized aneed for a metering instrument for both measuring and outputtingvolumetric flow rate, mass flow rate, and density of a fuel gas withoutresorting to a complex device. Applicant has further recognized that anaccuracy of approximately 2-4% for a flow meter can be acceptable as atrade-off for having less costly, less maintenance intensive integratedmetering instrument, rather than a separate and complex analyzer.

SUMMARY OF THE INVENTION

In view of the foregoing, embodiments of the present inventionadvantageously and uniquely integrate well-known industrial flow meteroperating principles into a single industrial instrument. Embodiments ofthe present invention provide a simple, low-cost flow meteringcomponents integrated into a single flow metering device capable ofmeasuring process fluid density as well as flow rate. Advantageously,embodiments of the present invention contain no moving parts and verylittle required maintenance.

An embodiment of the present invention also advantageously provides asystem for measuring fluid flow characteristics in a pipeline to providea volumetric flow rate, a mass flow rate, and density of flowing fluid.Further embodiments of the present invention further advantageouslyprovide a process density meter for measuring fluid flow characteristicsin a pipeline. Another embodiment of the present inventionadvantageously provides a method for measuring flowing fluidcharacteristics in a pipeline.

More particularly, the system for measuring fluid flow characteristicsin a pipeline according to an embodiment of the present inventionincludes a pipeline having a passageway having a longitudinal axis totransport fluid therethrough. The fluid can be in the form of aplurality of various types of liquids or gases, such as a combustiongas, or a mixture thereof.

The system also has a process density meter preferably having at leastportions thereof positioned within a fluid passageway of the pipeline.In the typical configuration, the bulk of the electronics, other thansensors (described below) are located external to the pipeline and thesensors and related equipment are located within the confines of thepipeline. The process density meter can include a process density meterhousing to house the sensors and related equipment and to support avortex-shedding body of a vortex measuring device within the flowingfluid of the pipeline.

The process density meter includes a vortex-shedding body positionedwithin the fluid passageway of the pipeline. The vortex-shedding body ispreferably in the form of a three-dimensional bluff body having anupstream side and a plurality of downstream sides. In the preferredconfiguration, the vortex-shedding body is adapted to connect to thepipeline or pipeline housing on opposite sides within the fluidpassageway of the pipeline. The vortex-shedding body includes anupstream surface positioned transverse to the longitudinal axis of thepipeline which have or contain a plurality of total pressure inlet portspositioned in the upstream surface. The vortex-shedding body alsoincludes a plurality of downstream surfaces which have or contain aplurality of static pressure inlet ports positioned in at least one ofthe downstream surfaces. The total pressure ports and static pressureports can be used in conjunction with a differential pressure sensingdevice such as a pitot-type differential pressure meter, describedbelow. The plurality of upstream ports and downstream ports provide theability to average the pressures across the vortex-shedding body withinthe pipeline, thus improving meter accuracy, and serve to resistplugging, minimizing the need for maintenance on the process densitymeter. Having the plurality of downstream surfaces, rather than acylindrical shape, can improve vortex-shedding and delineation betweenthe total and static pressures. The vortex-shedding body also can have athermal sensor inlet port, typically positioned in the upstream surface,and correspondingly, a thermal sensor outlet port positioned in at leastone of the downstream surfaces. A fluid passageway extends between thethermal sensor inlet port and the thermal sensor outlet port so thatfluid flowing through the pipeline passes therethrough for use with athermal flow sensing device such as the thermal flow meter.

The process density meter also includes a vortex measuring device suchas a vortex meter. The vortex meter measures the frequency of vorticesshed from the vortex-shedding body to produce a signal indicative ofvolumetric fluid flow rate within the pipeline. The vortex meterincludes a memory, a vortex frequency sensor, and a volumetric flow ratecalculator. The memory stores pipeline volume data for use by thevolumetric flow rate calculator. The pipeline volume data generallyincludes the inner diameter of the pipeline along with other data asknown to those skilled in the art necessary to determine cross-sectionalarea of the inner dimensions of the pipeline. The vortex frequencysensor senses the frequency of vortices shed by the vortex-shedding bodyto thereby produce a fluid flow rate signal responsive to the frequencyof vortices shed by the vortex-shedding body. The vortex frequencysensor is preferably in the form of a strain gauge or pressuretransducer but can embody other forms and still be within the scope ofthe present invention. The volumetric flow rate calculator, positionedto receive the pipeline volume data stored in the memory and the flowrate signal from the vortex frequency sensor, calculates a volumetricflow rate signal indicative of volumetric flow rate of fluid whenflowing through the pipeline.

The vortex-shedding body of the process density meter further includes atotal pressure manifold positioned in the vortex-shedding body andadjacent the upstream surface. The total pressure manifold has aplurality of total pressure inlet channels which are preferablycoaxially aligned with the plurality of total pressure inlet ports inthe upstream surface, and a total pressure outlet channel which is influid communication with the plurality of total pressure inlet channelsso that a first portion of fluid when flowing through the pipelinepasses into and through each of the total pressure inlet ports and outof the total pressure outlet channel. The vortex-shedding body alsoincludes a static pressure manifold positioned in the vortex-sheddingbody and adjacent the downstream surface or services having thecorresponding static pressure inlet ports. The static pressure manifoldhas a plurality of static pressure inlet channels aligned with theplurality of static pressure inlet ports and a static pressure outletchannel so that a second portion of fluid when flowing through thepipeline passes into and through each of the static pressure inlet portsand out of the static pressure outlet channel.

The process density meter also includes a differential pressuremeasuring device such as a differential pressure meter. The differentialpressure meter is preferably positioned adjacent the vortex-sheddingbody. The differential pressure meter includes a total pressure inletpositioned to receive fluid flowing through the total pressure manifoldoutlet channel, and a static pressure inlet positioned to receive fluidflowing through the static pressure manifold outlet channel. Thedifferential pressure meter also includes a differential pressureconverter positioned to receive fluid pressure from the total pressureinlet and the static pressure inlet and to produce a differentialpressure meter flow rate signal proportional to density of fluid whenflowing through the pipeline.

In an embodiment of the present invention, the differential pressuremeter is positioned also to receive an ambient temperature signal and astatic pressure signal. The ambient temperature signal can be eitherfrom an ambient temperature sensor associated with the thermal flowmeter (described later) or separate ambient temperature sensor. Thestatic pressure signal can be either from the differential pressureconverter, a tap in the static pressure inlet, or determined from aseparate static pressure sensor. The ambient temperature signal andstatic pressure signal can be used by the differential pressure meter toproduce a temperature and pressure compensated differential pressuremeter flow rate signal. If the differential pressure meter, however, isnot so equipped to accept such inputs for compensating the differentialpressure meter flow rate signal for pressure and temperature, a separatesignal conditioner can be used either on the differential pressure meterflow rate signal or on a later calculated density signal.

Advantageously, in an embodiment of the present invention, the processdensity meter can include a thermal flow measuring device, such as athermal flow meter, appropriately positioned to produce a mass flow ratesignal indicative of a mass flow rate of fluid when flowing through thepipeline. The thermal flow meter can have one or multiple thermal flowmeter elements installed in, on, or next to the leading edge of thevortex shedding meter body, but is preferably positioned within thevortex-shedding body to minimize electrical wiring requirements.

The process density meter further includes a fluid characteristicdeterminer positioned in communication with the vortex meter, thedifferential pressure meter, and the thermal flow meter, to processsensed signals therefrom. The fluid characteristic determiner includes afluid density calculator and a fluid mass flow rate calculator. Thefluid density calculator is responsive to the volumetric flow ratesignal received from the vortex meter and the differential pressuremeter flow rate signal received from the differential pressure meter andis positioned to calculate a density signal indicative of flowing fluiddensity.

Advantageously, in an embodiment where the process density meterincludes the vortex meter, the differential pressure meter, and athermal flow meter, the process density meter can also include averifier responsive to the density signal and the mass flow rate signalfrom the fluid characteristic determiner to verify the accuracy of thedensity signal and the mass flow rate signal from the fluidcharacteristic determiner. To perform the density comparison, theverifier has its own fluid density calculator responsive to the massflow rate signal from the thermal flow meter and the volumetric flowrate signal from the vortex meter to calculate a verification densitysignal to be used to compare with the density signal from the fluiddensity calculator of the fluid characteristic determiner. If bothdensity signals are within a minimum tolerance of each other, such as4%, the verifier can output a signal indicating a minimum accuracy ofthe process density meter.

To perform the density comparison, the verifier also has a comparatorthat is responsive to the density signal from the fluid characteristicdeterminer and is positioned to receive the density signal from thefluid density calculator of the verifier to compare the density signalfrom the fluid characteristic determiner with the density signal fromthe fluid density calculator of the verifier to verify reliability ofthe density signal from the fluid characteristic determiner and tooutput a density verification signal indicating verified density and tothereby determine the accuracy of the density signal from the fluidcharacteristic determiner.

To perform the mass flow rate comparison, the comparator of the verifieris also responsive to the mass flow rate signal from the fluidcharacteristic determiner and is positioned to receive the mass flowrate from the thermal flow meter to compare the mass flow rate signalfrom the fluid characteristic determiner with the mass flow rate signalfrom the thermal flow meter to verify reliability of the mass flow ratefrom the fluid characteristic determiner and to output a mass flow rateverification signal indicating verified mass flow rate and to therebydetermine the accuracy of the mass flow rate signal from the fluidcharacteristic determiner.

The system for measuring fluid flow characteristics in a pipeline canalso include a fluid characteristic display positioned external to thefluid passageway of the pipeline. The fluid characteristic display is incommunication with the process density meter and is typically positionedremote from the process density meter sensors. The fluid characteristicdisplay is positioned to receive the volumetric flow rate signal, thefirst density signal, and the second mass flow rate signal from theprocess density meter to display volumetric flow rate, flowing fluiddensity, and mass flow rate of the flowing fluid to a user thereof. Thevolumetric flow rate is preferably received from the vortex meter. Thedensity signal and mass flow rate signals are typically from the fluidcharacteristic determiner. If a signal conditioner is utilized andimplemented to condition the signals from the fluid characteristicdeterminer, however, the density signal and mass flow rate signal can befrom the signal conditioner. Also, where the process density meter isconfigured with a verifier, the fluid characteristic display further candisplay a density verified and the mass flow rate verified indication.

In another an embodiment of the present invention, the system formeasuring fluid flow characteristics in a pipeline includes a pipelinehaving a passageway with a longitudinal axis to transport fluidtherethrough, a process density meter, a thermal flow meter, and a fluidcharacteristic determiner. The process density meter, preferably havingat least portions thereof positioned within a first fluid passageway ofthe pipeline, can include a vortex-shedding body positioned within thefirst fluid passageway of the pipeline, a vortex meter positionedadjacent the vortex-shedding body, and a volumetric flow ratecalculator. The vortex-shedding body is preferably in the form of athree-dimensional bluff body having an upstream side or surfacepositioned transverse to the longitudinal axis of the first fluidpassageway, and a plurality of downstream sides or surfaces. Thevortex-shedding body also can have a thermal sensor inlet port,typically positioned in the upstream surface, and correspondingly, athermal sensor outlet port positioned in at least one of the downstreamsurfaces. A second fluid passageway extends between the thermal sensorinlet port and the thermal sensor outlet port so that fluid flowingthrough the pipeline passes therethrough. The vortex meter includes amemory having pipeline volume data stored therein, and a vortexfrequency sensor positioned adjacent the vortex-shedding body to sensethe frequency of vortices shed by the vortex-shedding body, to therebyproduce a fluid flow rate signal responsive to the frequency of vorticesshed by the vortex-shedding body. The volumetric flow rate calculator,positioned to receive the pipeline volume data stored in the memory andthe flow rate signal from the vortex frequency sensor, calculates avolumetric flow rate signal indicative of volumetric flow rate of fluidwhen flowing through the pipeline.

The thermal flow meter, positioned to produce a mass flow rate signalindicative of a mass flow rate of fluid when flowing through thepipeline, includes a thermal flow probe and a thermal flow meter massflow signal calculator. The thermal flow probe is positioned within thesecond fluid passageway extending between the thermal sensor inlet portand thermal sensor outlet port in the vortex shedding body to house aplurality of thermal sensors which are positioned to provide thermalenergy and to sense temperature of a portion of fluid when flowingthrough the pipeline. The thermal flow meter mass flow signal calculatorcalculates the mass flow rate signal, responsive to the plurality ofthermal sensors.

The fluid characteristic determiner, positioned in communication withthe vortex meter and the thermal flow meter, processes sensed signalstherefrom. The fluid characteristic determiner includes a fluid densitycalculator which, responsive to the volumetric flow rate signal receivedfrom the vortex meter and mass flow rate signal received from thethermal flow meter, calculates a density signal indicative of flowingfluid density.

Advantageously, a further embodiment of the present invention alsoincludes a process density meter for measuring fluid flowcharacteristics in a pipeline including a fluid passageway having alongitudinal axis to transport fluid therethrough, and having at leastportions thereof positioned within a fluid passageway of the pipeline.The process density meter generally includes a vortex meter andassociated equipment and a thermal flow meter and associated equipment,a fluid characteristic determiner, and a fluid characteristic displaypositioned external to the first fluid passageway of the pipeline, incommunication with the vortex meter and the fluid characteristicdeterminer, and positioned to receive a volumetric flow rate signal fromthe vortex meter, a mass flow rate from the thermal flow meter, and afluid density signal from the fluid characteristic determiner to displayvolumetric flow rate, density, and mass flow rate of the flowing fluid,to a user thereof.

In this embodiment of the present invention, in the typicalconfiguration, the bulk of the electronics, other than sensors, arelocated external to the pipeline, and the sensors and related equipmentare located within the confines of the pipeline. The process densitymeter can include a process density meter housing to house the sensorsand related equipment and to support a vortex-shedding body of a vortexmeasuring device within the flowing fluid of the pipeline.

The process density meter includes a vortex-shedding body positionedwithin the fluid passageway of the pipeline. The vortex-shedding body ispreferably in the form of a three-dimensional bluff body having anupstream side and a plurality of downstream sides. The vortex-sheddingbody is preferably adapted to connect to the pipeline or pipelinehousing on opposite sides within the fluid passageway of the pipeline,but can be less than the diameter of the pipeline or pipeline housing.The vortex-shedding body includes an upstream surface positionedtransverse to the longitudinal axis of the pipeline which preferably hasor contains a thermal sensor inlet port. The vortex-shedding body alsoincludes a plurality of downstream surfaces, at least one of whichpreferably has or contains a thermal sensor outlet port. A fluidpassageway extends between the thermal sensor inlet port and the thermalsensor outlet port so that fluid flowing through the pipeline passestherethrough for use with a thermal flow sensing device such as thethermal flow meter.

The process density meter also includes a vortex meter. The vortex metermeasures the frequency of vortices shed from the vortex-shedding body toproduce a signal indicative of volumetric fluid flow rate within thepipeline. The vortex meter includes a memory, a vortex frequency sensor,and a volumetric flow rate calculator. The memory stores pipeline volumedata for use by the volumetric flow rate calculator. The pipeline volumedata generally includes the inner diameter of the pipeline along withother data as known to those skilled in the art necessary to determinecross-sectional area of the inner dimensions of the pipeline. The vortexfrequency sensor senses the frequency of vortices shed by thevortex-shedding body to thereby produce a fluid flow rate signalresponsive to the frequency of vortices shed by the vortex-sheddingbody. As stated with regard to the previous embodiments, the vortexfrequency sensor is preferably in the form of a strain gauge or pressuretransducer but can embody other forms. The volumetric flow ratecalculator, positioned to receive the pipeline volume data stored in thememory and the flow rate signal from the vortex frequency sensor,calculates a volumetric flow rate signal indicative of volumetric flowrate of fluid when flowing through the pipeline.

The process density meter advantageously includes a thermal flow meter.The thermal flow meter is appropriately positioned to produce a massflow rate signal indicative of a mass flow rate of fluid when flowingthrough the pipeline. The thermal flow meter can have one or multiplethermal flow meter elements installed in, on, or next to the leadingedge of the vortex shedding meter body, but is preferably positionedwithin the vortex-shedding body to minimize electrical wiringrequirements. The thermal flow meter can include a thermal flow probe tohouse a plurality of thermal sensors and optionally positioned withinthe fluid passageway extending between the thermal sensor inlet port andthermal sensor outlet port in the vortex-shedding body. When sopositioned, the thermal flow probe typically has a thermal sensor inletpositioned in fluid communication with the thermal sensor inlet port inthe upstream surface of the vortex-shedding body to allow a portion offluid flowing through the fluid passageway to enter the thermal flowprobe and a thermal sensor outlet positioned in fluid communication withthe thermal sensor outlet port in at least one of the downstreamsurfaces of the vortex-shedding body to allow the portion of fluid toexit the thermal flow probe. A thermal probe channel extends between thethermal sensor inlet and the thermal sensor outlet so that a portion offluid when flowing through the thermal sensor inlet port passes into andthrough the thermal sensor inlet and so that the portion of fluidpassing into and through the thermal sensor inlet passes out of thethermal sensor outlet and out of the thermal sensor outlet port. Asstated above, although the thermal flow probe is described as positionedwithin the vortex-shedding body, the thermal flow probe can bealternatively positioned on or next to the vortex-shedding body providedthe thermal flow probe is able to receive or “see” the flowing fluid andthe flow through the thermal flow probe is either not obstructed or thethermal flow meter compensates for the disturbed flow resulting from theobstruction.

An ambient temperature sensor is preferably positioned within thethermal probe channel to detect ambient temperature of the portion offluid flowing between the thermal sensor inlet and thermal sensoroutlet. A thermal flow detection sensor is also preferably positionedwithin the thermal probe channel to sense an amount of thermal energyremoved by the portion of fluid flowing between the thermal sensor inletand the thermal sensor outlet. The thermal flow meter includes a thermalflow meter mass flow signal calculator responsive to the ambienttemperature sensor and the thermal flow detection sensor to calculatethe mass flow rate signal of the thermal flow meter.

The fluid characteristic determiner includes the primary calculatorassembly of the process density meter. The fluid characteristicdeterminer is positioned in communication with the vortex meter and thethermal flow meter, to process sensed signals therefrom. The fluidcharacteristic determiner includes a fluid density calculator and afluid mass flow rate calculator. The fluid density calculator isresponsive to the volumetric flow rate signal received from the vortexmeter and the thermal flow meter mass flow rate signal received from themass flow rate meter and is positioned to calculate a density signalindicative of flowing fluid density.

Advantageously, a fluid characteristic display of the process densitymeter is in electrical communication with the process density meter andis typically positioned remote from the process density meter sensors.The fluid characteristic display is positioned to receive the volumetricflow rate signal, the density signal, and the second mass flow ratesignal to display volumetric flow rate, flowing fluid density, and massflow rate of the flowing fluid to a user thereof. The volumetric flowrate is preferably received directly from the vortex meter. The densitysignal is received from the fluid characteristic determiner, and themass flow rate signal is preferably directly from the thermal flowmeter, though other methodologies are within the scope of the presentinvention.

An embodiment of the present invention also advantageously provides amethod for measuring flowing fluid characteristics in a pipeline using aprocess density meter having at least portions thereof positioned withina fluid passageway of the pipeline. Generally, the method includespositioning a vortex-shedding (bluff) body within a pipeline; measuringthe frequency of the vortices shed from the vortex-shedding body;determining volumetric flow rate; measuring the differential between thepressure experienced on the flow side of the vortex-shedding body andthe static pressure of the fluid in the pipeline; measuring the staticpressure and ambient temperature of the fluid in the pipeline;determining density and mass flow rate; and outputting density, massflow rate, and volumetric flow rate.

More specifically, after predetermining a cross-sectional area of apipeline having a flowing fluid and installing a vortex-shedding bluffbody generally positioned across the inner diameter of the pipeline,transverse to the direction of a flowing fluid, the user, measures thevortex frequency shedding rate generated by the vortex-shedding body.The vortex meter typically determines volumetric flow rate bycalculating the product of the fluid flow rate as determined from thevortex frequency sensor and the cross-sectional area of the column fluidflowing within the pipeline.

The user also installs an ambient temperature sensor positioned to beable to sample the temperature of the flowing fluid within the pipelineunaffected by other components of the present invention. The ambienttemperature of the flowing fluid and static pressure of the flowingfluid is measured.

The user installs a differential pressure meter, preferably in the formof an averaging pitot tube meter, to interface with the vortex-sheddingbody. The differential pressure meter measures the total pressure of theflowing fluid on the vortex-shedding body and the static pressure of theflowing fluid and can determine the differential pressure between atotal and static pressures. The differential pressure meter outputs adensity dependent flow rate signal that is typically proportional to avolumetric flow rate but can be proportional to other density and flowrate dependent values. The differential pressure meter output signal canbe corrected for temperature and pressure by the differential pressuremeter.

A true flowing fluid specific gravity can be determined from thepredetermined base specific gravity, the vortex meter flowing fluid flowrate, and density dependent differential pressure meter flow rate.Density of the flowing fluid can correspondingly be determined from theflowing fluid specific gravity and base density by a fluidcharacteristic determiner having a fluid density calculator. Mass flowcan also be calculated from the flowing fluid density calculated by thefluid characteristic determiner and volumetric flow rate from the vortexmeter. A fluid characteristic display can be positioned to receive thedensity, volumetric flow rate, and mass flow rate and display each.

Where the configuration selected for the differential pressure meterdoes not provide for pressure and temperature compensation, the densityand mass flow calculation can be inaccurate. A signal conditioner candetermine density corrected for pressure and temperature from the staticpressure of the differential pressure meter and ambient temperature ofthe independent ambient temperature sensor or ambient temperature sensorof a thermal flow meter, if so configured. Correspondingly, the signalconditioner can determine mass flow rate, a function of density andvolumetric flow rate, corrected for pressure and temperature. In eitherconfiguration, density and mass flow rate, along with volumetric flowrate from the flow meter, can be output to the fluid characteristicdisplay in a manner known and understood by those skilled in the art.

In an embodiment of the present invention the user can install a thermalflow meter adjacent the vortex-shedding body. If so installed, thethermal flow meter is capable of measuring a thermal energy change andoutputting a signal indicative of mass flow rate independent of densityso that the density and mass flow rate calculated from the differentialpressure meter flow rate signal can be verified. The mass flow rate,which is not fluid-density dependent, can be determined directly fromthe mass flow meter. A verifier having its own fluid density calculatorcan determine density from the mass flow rate signal of the thermal flowmeter in conjunction with the volumetric flow rate signal from thevortex meter. The verifier, having a comparator, can also compare thedensity signal determined from the differential pressure meter flow ratesignal with the density signal from the density calculator of theverifier in order to verify reliability of the density determined fromthe differential pressure meter flow rate signal. If the density signalis within a preselected tolerance, the verifier can output a densityverified signal to the fluid characteristic display. The comparator canalso compare the mass flow signal determined from the differentialpressure meter flow rate signal with the mass flow rate signal from thethermal flow meter in order to verify reliability of the mass flow ratedetermined from the differential pressure meter flow rate signal iswithin preselected tolerance. If so, the verifier can output a mass flowrate verified signal to the fluid characteristic display.

In another embodiment of the present invention, as with the previousembodiment, the user preferably predetermines a cross-sectional area ofa pipeline having a flowing fluid. The user installs the vortex-sheddingbluff body. The user also installs a vortex frequency detection device,part of a vortex meter, in the vortex-shedding body, the housing, or ina position on, in, or within the pipeline in the vicinity of thevortex-shedding body. As fluid flows through the pipeline, thevortex-shedding body causes vortices to be shed. The vortex metermeasures the frequency of Von Karman vortices shed by a vortex-sheddingbody. The vortex meter then determines volumetric flow rate of theflowing fluid from the flowing fluid rate measured by the vortexfrequency sensor and predetermined pipeline volumetric data, generallystored in the memory of the vortex meter, and outputs a respectivevortex meter flowing fluid flow rate signal. The vortex meter typicallydetermines volumetric flow rate by calculating the product of the fluidflow rate as determined from the vortex frequency sensor and thecross-sectional area of the column fluid flowing within the pipeline.

The user also installs a thermal flow meter or similar device adjacentthe vortex-shedding body which is capable of measuring mass flow rateand outputting a signal indicative of mass flow rate that is independentof fluid density. A fluid characteristic determiner having a fluiddensity calculator can determine density from the vortex meter flowingfluid flow rate signal, and non-density dependent mass flow rate signalfrom the thermal flow meter. All three fluid characteristicmeasurements, density, mass flow rate, and volumetric flow rate can betranslated to the user through the fluid characteristic display or othermethodology as known and understood by those skilled in the art.

In an embodiment of the present invention, the system includes computerreadable medium that is readable by a computer for measuring fluid flowcharacteristics in a pipeline, such as the fluid characteristicdeterminer, the computer readable medium comprising a set ofinstructions that, when executed by the computer, cause the computer toperform the operations of receiving from a vortex meter, positionedadjacent a vortex shedding body, a volumetric flow rate signalindicative of volumetric flow rate of fluid when flowing through thepipeline, and receiving a differential pressure meter flow rate signalrepresenting a differential pressure across the vortex-shedding body,the differential pressure meter having a total pressure inlet portpositioned in the upstream surface of the vortex shedding body Theinstructions also include those for determining a first determineddensity and specific gravity dependent fluid flow rate, responsive tothe differential pressure meter flow rate signal and the volumetric flowrate signal.

In an embodiment of the present invention, the system includes acomputer readable medium that is readable by a computer for measuringfluid flow characteristics in a pipeline, such as the fluidcharacteristic determiner, the computer readable medium comprising a setof instructions that, when executed by the computer, cause the computerto perform the operations of receiving from a vortex meter, positionedadjacent a vortex shedding body, a volumetric flow rate signalindicative of volumetric flow rate of fluid when flowing through thepipeline, receiving from a non-density dependent mass flow rate meter,positioned adjacent the vortex shedding body, a mass flow rate signalindicating a measured mass flow rate of the fluid, determining a densityof the fluid, responsive to the non-density dependent mass flow ratesignal from the mass flow rate meter and the volumetric flow rate signalfrom the vortex meter, and displaying density, mass flow rate andvolumetric flow rate to a user thereof on a fluid characteristicdisplay.

Advantageously an embodiment of the present invention can provide aninstrument intended for use in industrial combustion processes using lowmolecular weight hydrocarbon fuel gases, but may be used in anyindustrial process where simple, low-cost, and maintenance free densityand fluid flow rate measurements are desired.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the features and advantages of theinvention, as well as others which will become apparent, may beunderstood in more detail, a more particular description of theinvention briefly summarized above may be had by reference to theembodiments thereof which are illustrated in the appended drawings,which form a part of this specification. It is to be noted, however,that the drawings illustrate only various embodiments of the inventionand therefore are not to be considered limiting of the invention's scopeas it may include other effective embodiments as well.

FIG. 1 is a schematic view of a system for measuring fluid flowcharacteristics in a pipeline according to an embodiment of the presentinvention;

FIG. 2 is a prospective sectional view of a system for measuring fluidflow characteristics in a pipeline according to an embodiment of thepresent invention;

FIG. 3 is a prospective sectional view of a system for measuring fluidflow characteristics in a pipeline according to another embodiment ofthe present invention;

FIG. 4 is a prospective sectional view of a system for measuring fluidflow characteristics in a pipeline according to another embodiment ofthe present invention;

FIG. 5 is a partial perspective sectional view of a process densitymeter according to an embodiment of the present invention;

FIG. 6 is a partial perspective sectional view of a section of thevortex shedding body of FIG. 5 according to an embodiment of the presentinvention;

FIG. 7 is a partial perspective sectional view of another embodiment ofthe process density meter according to another embodiment of the presentinvention;

FIG. 8 is a partial perspective sectional view of a section of thevortex shedding body of FIG. 7 according to an embodiment of the presentinvention;

FIG. 9 is a partial perspective sectional view of another embodiment ofthe process density meter of according to another embodiment of thepresent invention;

FIG. 10 is a functional block diagram illustrating a basic structure ofa process density meter circuit of FIG. 5 according to an embodiment ofthe present invention;

FIG. 11 is a functional block diagram illustrating a basic structure ofa process density meter circuit of FIG. 7 according to an embodiment ofthe present invention;

FIG. 12 is a functional block diagram illustrating a basic structure ofa process density meter circuit of FIG. 9 according to an embodiment ofthe present invention;

FIG. 13 is a flowchart of a method for measuring flowing fluidcharacteristics in a pipeline according to an embodiment of the presentinvention; and

FIG. 14 is a flowchart of a method for measuring flowing fluidcharacteristics in a pipeline according to another embodiment of thepresent invention.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, which illustrate embodiments ofthe invention. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theillustrated embodiments set forth herein. Rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art.Like numbers refer to like elements throughout. Prime notation, if used,indicates similar elements in alternative embodiments. Note, the term“adjacent” as used herein refers to a position that is within, on, ornear the object referenced.

As illustrated in FIGS. 1-14, embodiments of the present inventionadvantageously provide a system, meter, and methods for measuring fluidflow characteristics in a pipeline. In particular, the flowcharacteristics of primary interest relate to industrial combustionprocesses using low molecular weight hydrocarbon fuel gases but can beused in other processes where density and flow rate measurements arerequired. Of interest, many industrial facilities feed fuel gases totheir combustion processes, for example, combustion boilers. These fuelgases constantly change in hydrocarbon composition. For example, thefuel gases may include varying percentages of methane, ethane, andpropane. To maintain efficient fuel-air ratio combustion control, as aminimum, a user must know the hydrocarbon density, and thus the BTUcontent. Ideally, the user would also prefer both volumetric flow rateand mass flow rate. In an embodiment of the present invention, thesystem 30 includes a pipeline 31, a process density meter 33 positionedat least partially within the pipeline, and a fluid characteristicsdisplay device 35 positioned to display to the user volumetric flowrate, flowing fluid density, and mass flow rate of flowing fluid withinthe pipeline 31.

As perhaps best shown in FIGS. 1 and 2, the pipeline 31 includes a fluidpassageway 37 having a longitudinal axis 39 to transport fluid 41. Thefluid 41 can be in the form of a plurality of various types of liquidsor gases, such as a combustion gas, or a mixture thereof. The pipeline31 can be of varying lengths and diameters according to the needs of auser. The pipeline 31 is well known to those skilled in the art andgenerally includes upstream and downstream sections 43, 45, eachconnected at an interface 47, 49, using an attachment assembly includingfasteners such as a plurality of bolts positioned to connect a flange 51on the downstream end of the upstream section 43 with a flange 53 on theupstream end of the downstream section 45. The pipeline 31 has apredetermined inner diameter 55 and cross-sectional area.

The process density meter 33 is positioned at least partially within thepipeline 31. In the typical configuration, the bulk of the electronics,other than sensors (described below) are located external to thepipeline 31 and the sensors and related equipment are located within theconfines of the pipeline 31. The process density meter 33 can include aprocess density meter housing 61 to house the sensors and relatedequipment and to support a vortex-shedding body 63 of a vortex measuringdevice 65 within the flowing fluid 41 of the pipeline 31. In anembodiment of the present invention, the process density meter housing61 includes as a first end 67, a second end 69, and a fluid passageway71 extending therebetween. The process density meter housing 61 ispreferably positioned coaxially between a pair of upstream anddownstream sections 43, 45, of the pipeline 31. The process densitymeter housing 61 is adapted to connect between the upstream anddownstream sections 43, 45, through use of a connection assembly asknown and understood by those skilled in the art. In one configuration,the process density meter housing 61 is sized to match a section of thepipeline 31 such that the process density meter housing 61 has an innerdiameter 75 substantially the same as the predetermined inner diameter55 of the pipeline 31. Functionally, the process density meter housing61 becomes part of the pipeline 31 and is in fluid communication withflowing fluid 41 within the pipeline 31. Alternatively, as best shown inFIG. 3, the process density meter housing 61′ can be instead sized tofit within the section of the pipeline 31. In this configuration, theouter diameter 77 of the process density meter housing 61′ is preferablysubstantially the same diameter as the predetermined inner diameter 55of the pipeline 31. Also, as best shown in FIG. 4, instead of supplyinga separate process density meter housing, the sensors and associatedequipment (described in detail below) can be positioned and supportedwithin a section of the pipeline 31. In this configuration, the selectedsection pipeline 31 functionally becomes the process density meterhousing 61″.

FIGS. 1-9 illustrate a process density meter 33 including avortex-shedding body 63 positioned within the pipeline 31. Thevortex-shedding body 63 is preferably in the form of a three-dimensionalbluff body having an upstream side 81 and a plurality of downstreamsides 83, but can be in the form of a two-dimensional bluff body, suchas a cylinder (not shown), and still be within the scope of the presentinvention. The vortex-shedding body 63 is preferably shaped to produce aReynolds number in excess of approximately 20,000. In one configuration,the vortex-shedding body 63 is adapted to connect to the pipeline 31 orpipeline housing 33 on opposite sides within the fluid passageway of thepipeline 37 or fluid passageway 71 of the pipeline housing 61, as shownabove in FIGS. 2-4. Alternatively, the vortex-shedding body 63 need onlybe connected at one attachment point within the pipeline 31 or pipelinehousing 61 and still remain properly supported. The vortex-shedding body63 can be less than the diameter of the pipeline 31 or pipeline housing61, however, a more uniform reading of static and dynamic pressures(described later) can be obtained by having the vortex-shedding body 63full-length.

FIGS. 2, 5, and 6 illustrate a vortex-shedding body 63 including anupstream surface 81 positioned transverse to the longitudinal axis 39 ofthe pipeline 31 which have or contain a plurality of total pressureinlet ports 85 positioned in the upstream surface 81. Thevortex-shedding body 63 also includes a plurality of downstream surfaces83 which have or contain a plurality of static pressure inlet ports 87positioned in at least one of the downstream surfaces 83. The totalpressure ports 85 and static pressure ports 87 can be used inconjunction with a differential pressure sensing device such as apitot-type differential pressure meter 89, described below. Theplurality of upstream ports 85 and downstream ports 87 provide theability to average the pressures across the vortex-shedding body 63within the pipeline 31, thus improving meter accuracy, and serve toresist plugging, minimizing the need for maintenance on the processdensity meter 33. Having the plurality of downstream surfaces 83, ratherthan a cylindrical shape, can improve vortex-shedding and delineationbetween the total and static pressures.

In an embodiment of the present invention, as perhaps best shown inFIGS. 2 and 7, the vortex-shedding body 63 also has a thermal sensorinlet port 91, typically positioned in the upstream surface 81, andcorrespondingly, a thermal sensor outlet port 93 positioned in at leastone of the downstream surfaces 83. A fluid passageway 95 extends betweenthe thermal sensor inlet port 91 and the thermal sensor outlet port 93so that fluid flowing through the pipeline passes therethrough for usewith a thermal flow sensing device such as the thermal flow meter 97(described later).

FIGS. 10 and 11 illustrate a process density meter 33, according to twoembodiments of the present invention which also include a vortexmeasuring device such as a vortex meter 65. The vortex meter 65 measuresthe frequency of vortices shed from the vortex-shedding body 63 toproduce a signal indicative of volumetric fluid flow rate Q_(vortex)within the pipeline 31. The vortex meter 65 includes a memory 101, avortex frequency sensor 103, and a volumetric flow rate calculator 105.The memory 101 stores pipeline volume data for use by the volumetricflow rate calculator 105. The pipeline volume data generally includesthe inner diameter 55 of the pipeline 31 along with other data as knownto those skilled in the art necessary to determine cross-sectional areaof the inner dimensions of the pipeline 31. The vortex frequency sensor103, optionally positioned adjacent the vortex-shedding body 63, sensesthe frequency of vortices shed by the vortex-shedding body 63 to therebyproduce a fluid flow rate signal responsive to the frequency of vorticesshed by the vortex-shedding body 63. The vortex frequency sensor 103 ispreferably in the form of a strain gauge or pressure transducerpositioned in the vortex-shedding body 63 or within the pipeline housing33 but can embody other forms which may require different positioning,such as downstream of the vortex-shedding body 63, and still be withinthe scope of the present invention. The volumetric flow rate calculator105, positioned to receive the pipeline volume data stored in the memory101 and the flow rate signal from the vortex frequency sensor 103,calculates a volumetric flow rate signal indicative of volumetric flowrate of fluid 41 when flowing through the pipeline 31.

In a preferred configuration, the volumetric flow rate calculator 105 ofthe vortex meter 65 further is positioned to receive an ambienttemperature signal and a static pressure signal. The ambient temperaturesignal can be either from an ambient temperature sensor 111 associatedwith a thermal flow meter 97 (described later) or a separate ambienttemperature sensor 113 (FIG. 2). The static pressure signal can beeither from a differential pressure flow meter 89 (describe later) or aseparate static pressure sensor (not shown). The ambient temperature andstatic pressure can be used by the vortex meter 65 to produce atemperature and pressure compensated volumetric flow rate signal v bycompensating the flow rate signal for the temperature and pressureexperienced by the vortex frequency sensor 103. A volumetric flow rateQ_(vortex) can be calculated using the formula:Q _(vortex) =A×v,where A is the cross-sectional area of the portion of pipeline whereflow rate is measured and v is the fluid flow rate. Additionally, if theinner dimension of the pipeline housing is not substantially the same asthe inner dimension of the pipeline, the memory preferably includes acorrection factor.

FIGS. 5-7 illustrate a vortex-shedding body 63 of the process densitymeter 33 further including a total pressure manifold 115 positioned inthe vortex-shedding body 63 and adjacent the upstream surface 81. Thetotal pressure manifold 115 has a plurality of total pressure inletchannels 117 which are preferably coaxially aligned with the pluralityof total pressure inlet ports 85 in the upstream surface 81, and a totalpressure outlet channel 119 which is in fluid communication with theplurality of total pressure inlet channels 117 so that a first portionof fluid 41 when flowing through the pipeline 31 passes into and througheach of the total pressure inlet ports 85 and out of the total pressureoutlet channel 119. The vortex-shedding body 63 also includes a staticpressure manifold 121 positioned in the vortex-shedding body 63 andadjacent the downstream surface or surfaces 83 having the correspondingstatic pressure inlet ports 87. The static pressure manifold 121 has aplurality of static pressure inlet channels 123 aligned with theplurality of static pressure inlet ports 87 and a static pressure outletchannel 125 so that a second portion of fluid 41 when flowing throughthe pipeline 31 passes into and through each of the static pressureinlet ports 87 and out of the static pressure outlet channel 125. In analternative embodiment of the present invention, instead of the totalpressure manifold and static pressure manifolds 115, 121, thevortex-shedding body 63 can have a central cavity (not shown) to houseor support various alternative components of a differential pressuremeter 89 (described later).

The process density meter 33 also includes a differential pressuremeasuring device such as a differential pressure meter 89. Thedifferential pressure meter 89 is preferably positioned adjacent thevortex-shedding body 63. The differential pressure meter 89 includes atotal pressure inlet 127 positioned to receive fluid flowing through thetotal pressure manifold outlet channel 119, and a static pressure inlet129 positioned to receive fluid flowing through the static pressuremanifold outlet channel 125. In an embodiment where the vortex-sheddingbody 63 has a central cavity (not shown) rather than a total pressuremanifold 115 or static manifold 121, the differential pressure meter 89includes a total pressure extension tube (not shown) and a staticpressure extension tube (not shown), both having the plurality of inletchannels and ports which provide the functions of the above describedtotal pressure and static pressure manifolds 115, 121.

FIGS. 10 and 11 illustrate that a differential pressure meter 89 alsocan include a differential pressure converter 131 positioned to receivefluid pressure from the total pressure inlet 127 and the static pressureinlet 129 to produce a differential pressure meter flow rate signalproportional to density of fluid 41 when flowing through the pipeline31. Functionally, the total pressure inlet 127, through the upstreamports 85 of the vortex-shedding body, “sees” the total pressure of thefluid 41. This total pressure is the sum of the static pressure, thepressure a user would measure with a pressure gauge installed on thepipeline 31, plus the kinetic pressure of the flowing fluid 41, theresult of the impact effect of the flowing fluid 41 on the upstreamsurface 81 of the vortex-shedding body 63. The static pressure inlet129, through the downstream ports 87 of the vortex-shedding body 63,only “see” the static pressure. The calculation of the differencebetween the total pressure and the static pressure of the flowing fluid41 results in the kinetic pressure of the flowing fluid 41, which isrelated to fluid density and velocity.

In a preferred configuration, the differential pressure meter 89 ispositioned also to receive an ambient temperature signal and a staticpressure signal. The ambient temperature signal can be either from anambient temperature sensor 111 associated with the thermal flow meter 97(described later) or the separate ambient temperature sensor 113. Thestatic pressure signal can be either from the differential pressuremeter 89, a tap in the static pressure inlet 129, or determined from aseparate static pressure sensor (not shown). The ambient temperaturesignal and static pressure signal can be used by the differentialpressure meter 89 to produce a temperature and pressure compensateddifferential pressure meter flow rate signal. If the differentialpressure meter 89, however, is not so equipped to accept such inputs forcompensating the differential pressure meter flow rate signal forpressure and temperature, a separate signal conditioner 133 (describedlater) can be used either on the differential pressure meter flow ratesignal or on a later calculated density signal (described later).

The differential pressure flow meter 89, preferably in the form of anaveraging pitot tube-type measuring device, can employ a multitude ofmethodologies as known by those skilled in the art to produce thedifferential pressure meter flow rate signal that is proportional todensity of fluid when flowing through the pipeline. In a large number ofaveraging pitot tube differential pressure flow meters, the output ofthe meter is a signal proportional to the product of the density of thefluid and the square of the volumetric flow rate ρV². In the preferredconfiguration, according to an embodiment of the present invention,however, the output of the averaging pitot tube differential pressuremeter is in the form of either volumetric flow rate under standardconditions or pressure and temperature compensated volumetric flow rate.The following is an illustrative example for a calculation of thevolumetric flow rate (gas-standard conditions) using an averaging pitotequation:Q _(pitot) =C ¹ X{square root}h _(w) ^(x) p _(f,)

-   -   where C¹=F_(na) ^(x)K^(x)D^(2x)Y_(a) ^(x)F^(pb) ^(x)F^(tb)        ^(x)F^(tf) ^(x)F_(Sg) ^(x)F_(pv) ^(x)F_(aa),    -   and where    -   Q_(pitot) Standard Volumetric Flow Rate. This term is the flow        rate of the fluid passing the vortex-shedding body expressed in        standard volume units per unit of time. For this equation, the        base pressure is 14.73 psia and the base temperature is 60° F.    -   F_(na) Units Conversion Factor. This factor is used to convert        the flow rate to the desired or wanted set of units, typically        standard cubic feet per day.    -   K Flow Coefficient. This factor takes into account the diameter        of the pipeline and is expressed as a function of the Reynolds        number.    -   D Internal diameter of pipe, inches (mm).    -   Y_(a) Expansion Factor. This factor has little effect on flow        and thus, they can be estimated based on the typical gas that is        used in the application, with very little error.    -   F_(pb) Pressure Base Factor. This factor provides gas volumes at        a pressure base of 14.73 psia. F_(pb=14.73/base pressure, psia).    -   F_(tb) Temperature Base Factor. This factor is calculated to        give gas volumes at a base temperature of 60° F. and can be        calculated as: F_(tb=(base temperature (° F.)+460)/520.)    -   F_(tf) Flowing Temperature Factor. This factor corrects for        tabular data taking at a gas temperature other than 60° F.        F_(tf=520/{square root}(Flowing temperature (° F.)+460)).    -   F_(Sg) Specific Gravity Factor. This factor corrects the flow        equation whenever the gas is not air. The factor can be        calculated as: F_(Sg={square root}) ₁ _(/) _(SG) .    -   SG Specific Gravity of Flowing Liquid. Ratio of the density of        the flowing fluid to the density of water at 60° F.    -   F_(pv) Supercompressibility Factor. This factor accounts for the        deviation from the “ideal gas” laws and is typically determined        through testing at expected pressure and temperature conditions,        but can be estimated based on the typical gas used in the        application, with very little error.    -   F_(aa) Thermal Expansion Factor which corrects for the flowing        area change of the pipe at the vortex-shedding body location due        to temperature effects.    -   h_(w) Differential (kinetic) pressure expressed as the height,        in inches, of a water column at 68° F. at standard gravity        (g_(o)=32.174 ft/sec²=9.807 m/sec²).    -   P_(f) Flowing Pressure. This is the static pressure of the        pipeline expressed in psia.

As perhaps best shown in FIGS. 7, 8, and 11, advantageously, in anembodiment of the present invention, a process density meter 33 caninclude a thermal flow measuring device, such as a thermal flow meter97, appropriately positioned to produce a mass flow rate signalindicative of a mass flow rate of fluid 41 when flowing through thepipeline 31. The thermal flow meter 97 can have one or multiple thermalflow meter elements installed in, on, or next to the leading edge of thevortex-shedding body 63, but is preferably positioned within thevortex-shedding body 63 to minimize electrical wiring requirements.

More specifically, the thermal flow meter 97 preferably includes animmersion-type thermal flow probe 141 positioned to house a plurality ofthermal sensors and positioned within the fluid passageway 95 extendingbetween the thermal sensor inlet port 91 and thermal sensor outlet port93 in the vortex-shedding body 63. Though other types of thermal flowdetectors or sensors may be used and still be within the scope of thepresent invention, the immersion-type probes are simple, rugged,insensitive to particulate matter within the flowing fluid, and easilycleaned. The thermal flow probe 141 typically has a thermal sensor inlet143 positioned in fluid communication with the thermal sensor inlet port91 in the upstream surface 81 of the vortex-shedding body 63, and athermal sensor outlet 145 positioned in fluid communication with thethermal sensor outlet port 93 in at least one of the downstream surfaces83 of the vortex-shedding body 63. A thermal probe channel 147 extendsbetween the thermal sensor inlet 143 and the thermal sensor outlet 145so that a portion of fluid 41 when flowing through the thermal sensorinlet port 91 passes into and through the thermal sensor inlet 143, andso that the portion of fluid 41 passing into and through the thermalsensor inlet 143 passes out of the thermal sensor outlet 145 and out ofthe thermal sensor outlet port 93 (FIGS. 3 and 4). As stated above,although the thermal flow probe 141 is described as positioned withinthe vortex-shedding body 63, the thermal flow probe 141 can bealternatively positioned on or next to the vortex-shedding body 63provided the thermal flow probe 141 is able to receive or “see” theflowing fluid 41 and the flow through the thermal flow probe 141 iseither not obstructed or the thermal flow meter 97 compensates for thedisturbed flow resulting from the obstruction.

An ambient temperature sensor 111 is preferably positioned within thethermal probe channel 147 to detect ambient temperature of the portionof fluid 41 flowing between the thermal sensor inlet 143 and thermalsensor outlet 145. A thermal flow detection sensor 149 is alsopreferably positioned within the thermal probe channel 147 to sense anamount of thermal energy removed by the portion of fluid 41 flowingbetween the thermal sensor inlet 143 and the thermal sensor outlet 145.In the selected configuration of the thermal flow meter 97 describedwith respect to the figures, the thermal flow meter 97 further includesa thermal flow meter mass flow signal calculator 151 responsive to theambient temperature sensor 111 and the thermal flow detection sensor 149to produce either a voltage or a current required to maintain a constanttemperature differential between the ambient temperature sensor 111 andthe thermal flow detection sensor 149. This constant current or voltageis used to calculate the mass flow rate signal of the thermal flow meter97. If the fluid flow is obstructed when flowing through the thermalsensors of the thermal flow meter 97, the mass flow signal calculator151 of the thermal flow meter 97 can include a thermal mass flow signalcompensator 153 to compensate for an error induced by the obstructedflow.

FIG. 10 illustrates that a process density meter 33 can further includea fluid characteristic determiner 161 positioned in communication withthe vortex meter 65, the differential pressure meter 89, and the thermalflow meter 97, to process sensed signals therefrom. The fluidcharacteristic determiner 161 includes a fluid density calculator 163and can include a fluid mass flow rate calculator 165. In the preferredconfiguration, the fluid density calculator 163 is responsive to thevolumetric flow rate signal Q_(vortex) received from the vortex meter 65and the differential pressure meter flow rate signal Q_(pitot) receivedfrom the differential pressure meter 89 and is positioned to calculate adensity signal indicative of flowing fluid density Density_(flowing).

In the illustrative example for a calculation of the volumetric flowrate Q_(pitot) using an averaging pitot equation, described above, theF_(g) factor (F_(g)=(1/SG)^(1/2)) of the equation is the influence ofgas specific gravity (SG) on the averaging pitot tube, and this is whatprovides the ability to obtain density from the averaging pitot tubeflow rate calculation. For example, the SG_(base) used in the equationin the illustrative example is that of the flowing gas. When thespecific gravity of the flowing gas changes, the flow calculationQ_(pitot) must be compensated by multiplying it by the square root ofthe ratio of the base specific gravity divided by the true specificgravity.Q _(true) =Q _(pitot)*(SG _(base) /SG _(flowing))^(1/2).

Noting that the flow rate from the vortex meter is NOT influenced by thespecific gravity of the flowing gas, the volumetric flow rate Q_(vortex)from the vortex meter is equivalent to true volumetric flow rate:Q _(vortex) =Q _(true) =Q _(pitot)*(SG _(base) /SG _(flowing))^(1/2).By compensating the Q_(pitot) for changes in SG of the flowing gas, andmanipulating the equations, the true (flowing gas) specific gravity canbe determined:SG _(flowing) =SG _(base)*(Q _(pitot) /Q _(vortex))².

Correspondingly, density can be calculated as a factor true (flowinggas) specific gravity and base density:Density _(flowing) =Density _(base)*(SG _(flowing) /SG _(base)).

Similar to the fluid density calculator 163, in an embodiment of thepresent invention, the fluid mass flow rate calculator 165 is responsiveto the volumetric flow rate signal Q_(vortex) received from the vortexmeter 65 and the differential pressure meter flow rate signal Q_(pitot)received from the differential pressure meter 89 and is positioned tocalculate a mass flow rate signal indicative of flowing fluid mass flowrate Q_(massflow). After performing calculations similar to those above,the mass flow rate Q_(massflow) is then calculated as a function of theproduct of the flowing fluid density Density_(flowing) and thevolumetric flow rate Q_(vortex):Q _(massflow) =Density _(flowing) *Q _(vortex).

In an alternative configuration, the mass flow rate calculator 165 isinstead responsive to the flowing fluid density signal Density_(flowing)from the fluid density calculator 163 and the volumetric flow ratesignal Q_(vortex) from the vortex meter to calculate mass flowQ_(massflow).

FIGS. 7 and 11 illustrate that where the process density meter 33includes the vortex meter 65, the differential pressure meter 89, and athird meter to measure and output a non-density dependent mass flow ratesignal, such as the thermal flow meter 97, described above, the processdensity meter 33 can also include a verifier 171 responsive to thedensity signal and the mass flow rate signal from the fluidcharacteristic determiner 161 to verify the accuracy of the densitysignal and mass flow rate signal from the fluid characteristicdeterminer 161. To perform the density comparison, the verifier 171 hasits own fluid density calculator 173 responsive to the mass flow ratesignal from the thermal flow meter 97 and the volumetric flow ratesignal from the vortex meter 65 to calculate a verification densitysignal to be used to compare with the density signal from the fluiddensity calculator 163 of the fluid characteristic determiner 161. Ifboth density signals are within a minimum tolerance of each other, suchas 4%, the verifier 171 can output a signal indicating a minimumaccuracy of the process density meter 33 has been met.

To perform the density comparison, the verifier 171 also has acomparator 175 that is responsive to the density signal from the fluidcharacteristic determiner 161 and is positioned to receive the densitysignal from the fluid density calculator 173 of the verifier 171 tocompare the density signal from the fluid characteristic determiner 161with the density signal from the fluid density calculator 173 of theverifier 171 to verify reliability of the density signal from the fluidcharacteristic determiner 161, to output a density verification signalindicating verified density, and to thereby determine the accuracy ofthe density signal from the fluid characteristic determiner 161. Toperform the mass flow rate comparison, the comparator 175 of theverifier 171 is responsive to the mass flow rate signal from the fluidcharacteristic determiner 161 and is positioned to receive the mass flowrate Q_(thermal) from the thermal flow meter 97 to compare the mass flowrate signal Q_(massflow) from the fluid characteristic determiner 161with the mass flow rate signal from the thermal flow meter 97 to verifyreliability of the mass flow rate from the fluid characteristicdeterminer 161, to output a mass flow rate verification signalindicating verified mass flow rate, and to thereby determine theaccuracy of the mass flow rate signal from the fluid characteristicdeterminer 161. Note, the volumetric flow rate calculator 105,differential pressure converter 131, mass flow signal calculator 151,mass flow signal compensator 153, fluid density calculator 163, massflow rate calculator 165, verifier 171, and signal conditioner 133 canbe implemented in either hardware or software. Note also, the fluidcharacteristic determiner 161 can be implemented in the form of acomputer, and, though depicted separately, the signal conditioner 133and the verifier 171 can be processed by the fluid characteristicdeterminer 161. Further, the software of the fluid characteristicdeterminer 161, can be separately stored on a storage media readable bythe fluid characteristic determiner 161.

In an embodiment of the present invention, the process density meter 97can include a signal conditioner 133. As stated above, the signalconditioner 133 can be used either to pressure and temperaturecompensate the differential pressure meter flow rate signal from thedifferential pressure meter 89 or pressure and temperature compensatethe fluid density and mass flow rate signals from the fluidcharacteristic determiner 161 where the differential pressure meterselected is not capable of independently applying pressure andtemperature compensation directly to its output signal. For example, asbest shown in FIG. 11, when positioned to compensate the output signalsof the fluid characteristic determiner 161, the signal conditioner 133is responsive to the density signal and mass flow rate signals from thefluid characteristic determiner 161 and is positioned to receive atemperature signal from the ambient temperature sensor 111 of thethermal flow meter 97 or separate ambient temperature sensor 113 and astatic pressure signal from the differential pressure meter 89. Thesignal conditioner 133 conditions the density signal of the fluiddensity calculator 163 of the fluid characteristic determiner 161 toform a temperature and pressure compensated density signal andconditions the mass flow rate signal from the fluid mass flow ratecalculator 165 of the fluid characteristic determiner 161 to form atemperature and pressure compensated mass flow rate signal. Where theprocess density meter 33 is also configured with a verifier 171, thecomparator 175 of the verifier 171 receives the density signal and massflow rate signal from the signal conditioner 133 instead of directlyfrom the fluid characteristic determiner 161, as described above,otherwise all calculations are the same.

As best shown in FIGS. 1, 2, 10-11, a system 30 for measuring fluid flowcharacteristics in a pipeline, or alternatively the process densitymeter 33, itself, also includes a fluid characteristic display 35positioned external to the fluid passageway 37 of the pipeline 31. Thefluid characteristic display 35 is in electrical communication withother process density meter components and is typically located remotefrom the process density meter sensors. The fluid characteristic display35 is positioned to receive the volumetric flow rate signal, the densitysignal, and the mass flow rate signal to display volumetric flow rate182, flowing fluid density 183, and mass flow rate 184 of the flowingfluid. The volumetric flow rate is preferably received from the vortexmeter 65. The density signal and mass flow rate signals are typicallyfrom the fluid characteristic determiner 161, however, if a signalconditioner 133 is utilized and implemented to condition the signalsfrom the fluid characteristic determiner 161, the density signal andmass flow rate signal will instead be from the signal conditioner 133.Also, where the process density meter 33 is configured with a verifier171, the fluid characteristic display 35 further can display densityverified and mass flow rate verified indications 185, 186.

Advantageously, as perhaps best shown in FIGS. 9 and 12, anotherembodiment of the present invention also includes a process densitymeter 33 for measuring fluid flow characteristics in a pipeline 31including a fluid passageway 37 having a longitudinal axis 39 totransport fluid 41 therethrough and positioned at least partially withinthe pipeline 31. The process density meter 33 generally includes avortex-shedding measuring device and associated equipment, such as avortex meter 65, a mass flow rate measuring device and associatedequipment, such as a thermal flow meter 97, a fluid characteristicdeterminer 161, and a fluid characteristic display 35 which is locatedexternal to the fluid passageway 37 of the pipeline 31 and incommunication with the vortex meter 65 and the fluid characteristicdeterminer 161, and positioned to receive a volumetric flow rate signalfrom the vortex meter 65, a mass flow rate from the thermal flow meter97, and a fluid density signal from the fluid characteristic determiner161 to display volumetric flow rate, density, and mass flow rate of theflowing fluid to a user thereof.

As with the previous described embodiments, in the typicalconfiguration, the bulk of the electronics, other than sensors, arelocated external to the pipeline 31, and the sensors and relatedequipment are located within the confines of the pipeline 31. Theprocess density meter 33 can include a process density meter housing tohouse the sensors and related equipment and to support a vortex-sheddingbody 63 of the vortex meter 65 within the flowing fluid 41 of thepipeline 31. In one configuration, the process density meter housing 61is positioned coaxially between a pair of upstream and downstreamsections 43, 45, of the pipeline 31 (FIGS. 2). The process density meterhousing 61 is adapted to connect between the upstream and downstreamsections 43, 45, of the pipeline 31 through use of a connection assemblyas known and understood by those skilled in the art. The process densitymeter housing 61 is preferably sized to match a section of the pipeline31 such that the process density meter housing 61 has an inner diameter75 substantially the same as the predetermined inner diameter 55 of thepipeline 31. In a second configuration, as best shown in FIG. 3, theprocess density meter housing 61′ can be instead sized to fit within asection of the pipeline 31. In this configuration, the outer diameter 77of the process density meter housing 61′ is preferably substantially thesame diameter as the predetermined inner diameter 55 of the pipeline 31.In a third configuration, as best shown in FIG. 4, instead of supplyinga separate process density meter housing, the sensors and associatedequipment can be positioned and supported within a section of thepipeline 31. In this configuration, the pipeline 31 functions as aprocess density meter housing 61″.

FIGS. 4, 9 and 12 illustrate a process density meter 33 including avortex-shedding body 63 positioned within the pipeline 31. Thevortex-shedding body 63 is preferably in the form of a three-dimensionalbluff body having an upstream side 81 and a plurality of downstreamsides 83. The vortex-shedding body 63 is preferably adapted to connectto the pipeline 31 or pipeline housing 61 on opposite sides within thefluid passageway 41 of the pipeline 31, as perhaps best shown in FIG. 4,but can be less than the diameter of the pipeline 31 or pipeline housing61 and still be within the scope of the present invention.

FIGS. 4 and 9 illustrate a vortex-shedding body 63 including an upstreamsurface 81 positioned transverse to the longitudinal axis 39 of thepipeline 31 which preferably has or contains a thermal sensor inlet port91. The vortex-shedding body 63 also includes a plurality of downstreamsurfaces 83, at least one of which preferably has or contains a thermalsensor outlet port 93. A fluid passageway 95 extends between the thermalsensor inlet port 91 and the thermal sensor outlet port 93 so that fluidflowing through the pipeline passes therethrough for use with a thermalflow sensing device such as the thermal flow meter 97 (described later).

FIG. 12 illustrates that the process density meter 33 can also include avortex measuring device such as a vortex meter 65. The vortex meter 65measures the frequency of vortices shed from the vortex-shedding body 63to produce a signal indicative of volumetric fluid flow rate Q_(vortex)within the pipeline 31. The vortex meter 65, optionally positionedadjacent the vortex-shedding body, includes a memory 101, a vortexfrequency sensor 103, and a volumetric flow rate calculator 105. Thememory 101 stores pipeline volume data for use by the volumetric flowrate calculator 105. The pipeline volume data generally includes theinner diameter 55 of the pipeline 31 along with other data as known tothose skilled in the art necessary to determine cross-sectional area ofthe inner dimensions of the pipeline 31. The vortex frequency sensor103, senses the frequency of vortices shed by the vortex-shedding body63 to thereby produce a fluid flow rate signal responsive to thefrequency of vortices shed by the vortex-shedding body 63. As statedwith regard to the previous embodiments, the vortex frequency sensor 103is preferably in the form of a strain gauge or pressure transducerpositioned in the vortex-shedding body 63 or process density meterhousing 61 but can embody other forms and be positioned at otherlocations adjacent the vortex-shedding body 63 and still be within thescope of the present invention. The volumetric flow rate calculator 105,positioned to receive the pipeline volume data stored in the memory 101and the flow rate signal from the vortex frequency sensor 103,calculates a volumetric flow rate signal indicative of volumetric flowrate of fluid 41 when flowing through the pipeline 31. In anotherconfiguration, the volumetric flow rate calculator 105 of the vortexmeter 65 further is positioned to receive an ambient temperature signaland a static pressure signal. The ambient temperature signal can beeither from an ambient temperature sensor 111 associated with a thermalflow meter 97 or a separate ambient temperature sensor 113 (FIG. 4). Thestatic pressure signal can be from a separate static pressure sensor(not shown). The ambient temperature and static pressure can be used bythe vortex meter to produce a temperature and pressure compensatedvolumetric flow rate signal by compensating the flow rate signalcorresponding to the frequency of the vortices shed by thevortex-shedding body 63 for the temperature and pressure experienced bythe vortex frequency sensor 103. In both configurations, a volumetricflow rate Q_(vortex) can be calculated using the formula:Q _(vortex) =A×v,where A is the cross-sectional area of the portion of pipeline whereflow rate is measured and v is the fluid flow rate. Additionally, if theinner dimension 75 of the pipeline housing 61 is not substantially thesame as the inner dimension 55 of the pipeline, the memory 101preferably includes a correction factor.

The process density meter 33 advantageously includes a thermal mass flowdetection device such as a thermal flow meter 97. The thermal flow meter97 is appropriately positioned to produce a mass flow rate signalQ_(thermal) indicative of a mass flow rate of fluid 41 when flowingthrough the pipeline 31. The thermal flow meter 97 can have one ormultiple thermal flow meter elements installed in, on, or next to theleading edge of the vortex shedding meter body 63, but is preferablypositioned within the vortex-shedding body 63 to minimize electricalwiring requirements and to reduce the complexity of the process densitymeter 33.

The thermal flow meter 97 preferably includes an immersion-type thermalflow probe 141 positioned to house a plurality of thermal sensors andpositioned within the fluid passageway 95 extending between the thermalsensor inlet port 91 and thermal sensor outlet port 93 in thevortex-shedding body 63. The thermal flow probe 141 typically has athermal sensor inlet 143 positioned in fluid communication with thethermal sensor inlet port 91 in the upstream surface 81 of thevortex-shedding body 63 to allow a portion of fluid flowing through thefluid passageway 95 to enter the thermal flow probe 141, and a thermalsensor outlet 145 positioned in fluid communication with the thermalsensor outlet port 93 in at least one of the downstream surfaces 83 ofthe vortex-shedding body 63 to allow the portion of fluid to exit thethermal flow probe 141. A thermal probe channel 147 extends between thethermal sensor inlet 143 and the thermal sensor outlet 145 so that aportion of fluid 41 when flowing through the thermal sensor inlet port91 passes into and through the thermal sensor inlet 143, and so that theportion of fluid 41 passing into and through the thermal sensor inlet143 passes out of the thermal sensor outlet 145 and out of the thermalsensor outlet port 93 (FIG. 4). As stated above, although the thermalflow probe 141 is shown in the figures and described as positionedwithin the vortex-shedding body 63, the thermal flow probe 141 can bealternatively positioned on or next to the vortex-shedding body 63provided the thermal flow probe 141 is able to receive or “see” theflowing fluid 41 and the flow through the thermal flow probe 141 iseither not obstructed or the thermal flow meter 97 compensates for thedisturbed flow resulting from the obstruction.

An ambient temperature sensor 111 is preferably positioned within thethermal probe channel 147 to detect the ambient temperature of theportion of fluid 41 flowing between the thermal sensor inlet 143 andthermal sensor outlet 145. A thermal flow detection sensor 149 is alsopreferably positioned within the thermal probe channel 147 to sense anamount of thermal energy removed by the portion of fluid 41 flowingbetween the thermal sensor inlet 143 and the thermal sensor outlet 145.In the selected configuration of the thermal flow meter 97 describedwith respect to the figures, the thermal flow meter 97 includes athermal flow meter mass flow signal calculator 151 responsive to theambient temperature sensor 111 and the thermal flow detection sensor 149to produce either a voltage or a current required to maintain a constanttemperature differential between the ambient temperature sensor 111 andthe thermal flow detection sensor 149. This constant current or voltageis used to calculate the mass flow rate signal Q_(thermal) of thethermal flow meter 97. If the fluid flow is obstructed when flowingthrough the thermal sensors of the thermal flow meter 97, for example,where the thermal probe channel 147 is not parallel to the longitudinalaxis 39 of the pipeline 31 due to non-symmetric positioning of theupstream surface 81 of the vortex-shedding body 63 or non-symmetricpositioning of the thermal flow probe 141 or channel 147, the mass flowsignal calculator 151 of the thermal flow meter 97 can include a thermalmass flow signal compensator 153 to compensate for an error induced bythe obstructed flow.

The fluid characteristic determiner 161 includes the primary calculatorassembly of the process density meter 33. The fluid characteristicdeterminer 161 is positioned in communication with the vortex meter 65and the thermal flow meter 97, to process sensed signals therefrom. Thefluid characteristic determiner 161 includes a fluid density calculator163. Although the fluid characteristic determiner may include a massflow calculator, the mass flow rate calculator is not required accordingto this embodiment of the present invention as the thermal flow meter 97directly produces a signal Q_(thermal) indicative of a mass flow rate offluid 41 when flowing through the pipeline 31. The fluid densitycalculator 163 is responsive to the volumetric flow rate signalQ_(vortex) received from the vortex meter 65 and the thermal flow metermass flow rate signal Q_(thermal) received from the mass flow rate meter97 and is positioned to calculate a density signal indicative of flowingfluid density Density_(flowing), where:Density _(flowing) =Q _(thermal) /Q _(vortex).

FIG. 12 illustrates a fluid characteristic display 35 positionedexternal to the fluid passageway 37 the pipeline 31 of the processdensity meter 33 (FIG. 2) in communication with other components of theprocess density meter 33 and typically positioned remote from theprocess density meter sensors. The fluid characteristic display 35 ispositioned to receive the volumetric flow rate signal, the densitysignal, and the second mass flow rate signal to display volumetric flowrate 182, flowing fluid density 183, and mass flow rate 184 of theflowing fluid 41. The volumetric flow rate is preferably receiveddirectly from the vortex meter 65. The density signal is received fromthe fluid characteristic determiner 161, and the mass flow rate signalis preferably directly from the thermal flow meter 97, though othermethodologies of establishing a signal connection are within the scopeof the present invention.

An embodiment of the present invention also advantageously provides amethod for measuring flowing fluid characteristics in a pipeline using aprocess density meter having at least portions thereof positioned withina fluid passageway of the pipeline. Generally, the method includespositioning a vortex-shedding (bluff) body within a pipeline; measuringthe frequency of the vortices shed from the vortex-shedding body;determining volumetric flow rate; measuring the differential between thepressure experienced on the flow side of the vortex-shedding body andthe static pressure of the fluid in the pipeline; measuring the staticpressure and ambient temperature of the fluid in the pipeline;determining density and mass flow rate; and outputting density, massflow rate, and volumetric flow rate for display.

More specifically, as perhaps best shown in FIG. 13, a userpredetermines a cross-sectional area of a pipeline 31 having a flowingfluid 41 (block 201). The user installs the vortex-shedding body 63. Theinstallation can be accomplished by individually installing thevortex-shedding body 63 within an existing piece of pipeline 31 (FIG.4), or by installing the vortex-shedding body 63 within a housing 61which can be positioned coaxially between an upstream and a downstreamsection 43, 45, of the pipeline 31 (FIG. 2) or within a pipelineinterior passageway 37 (FIG. 3). The vortex-shedding body 63 isgenerally positioned across the inner diameter 55 of the pipeline,transverse to the direction of a flowing fluid 41. The upstream surface81 of the vortex-shedding body 63 is preferably placed perpendicular tothe direction of the flowing fluid 41. The vortex-shedding body 63causes the generation of Von Karman vortices when fluid 41 is flowingwithin the pipeline 31. The vortex-shedding body 63 also includesupstream ports 85 that are affected by fluid 41 flowing within thepipeline 31 having a total pressure equivalent to the sum of the kineticand static pressures of the flowing fluid 41. The vortex-shedding body63 further includes downstream ports 87 which are affected by fluid 41flowing within the pipeline 31 having only static pressure, and a pairof manifolds 115, 121, within the vortex-shedding body 63 toindividually channel fluid having total pressure separate from fluidhaving only static pressure.

The user also installs a vortex frequency detection device 103, part ofa vortex (shedding) meter 65, on, and, or within either thevortex-shedding body 63, the process density meter housing 61, or thepipeline 31, in the vicinity of the vortex-shedding body 63. The vortexfrequency sensor 103, as described above, typically takes the form of astrain-gauge, a pressure transducer, or an acoustic sensor. As fluidflows 41 through the pipeline 31, the bluff body (vortex-shedding) 63causes vortices to be shed. The vortex meter 65 measures (block 203) thefrequency of Von Karman vortices shed by a vortex-shedding body 63. Thevortex meter 65 then outputs a respective true vortex meter flowingfluid flow rate signal. The vortex meter can also determine and outputvolumetric flow rate (block 205) from the true flowing fluid ratemeasured by the vortex frequency sensor in conjunction withpredetermined pipeline volumetric data, generally stored in the memoryof the vortex meter. The vortex meter 65 typically determines volumetricflow rate by calculating the product of the fluid flow rate asdetermined from the vortex frequency sensor 103 and the cross-sectionalarea of the column fluid 41 flowing within the pipeline 31. Othermethodologies of determining the pipeline flowing fluid rate andcorrespondingly the volumetric flow rate through use of avortex-shedding body, known and understood by those skilled in the artare, of course, within the scope of the present invention.

The user installs a differential pressure meter 89, preferably in theform of an averaging pitot tube, to interface with the vortex-sheddingbody 63. The user also installs either a thermal flow program 141 havingambient temperature sensor 111 or a separate ambient temperature sensor113 positioned to be able to sample the temperature of the flowing fluid41 within the pipeline 31, generally unaffected by other components ofthe present invention. The ambient temperature sensor 113 is typicallyin the form of a thermistor but can be another type of sensor known andunderstood by those skilled in the art. The ambient temperature of theflowing fluid 41 and static pressure of the flowing fluid 41 is measured(block 207). The differential pressure meter 89 measures the totalpressure of the flowing fluid 41 on the vortex-shedding body 63 and thestatic pressure of the flowing fluid and can determine the differentialpressure (block 209) between a total and static pressures. Thedifferential pressure meter further determines (block 211) and outputs adensity dependent flow rate signal that is typically proportional to avolumetric flow rate but can be proportional to other density and flowrate dependent values. In some configurations, the differential pressuremeter output signal can be corrected for temperature and pressure by thedifferential pressure meter.

A true flowing fluid specific gravity can be determined (block 213) fromthe predetermined base specific gravity of the fluid, the vortex meterflowing fluid flow rate, and density dependent differential pressuremeter flow rate. Density of the flowing fluid 41 can correspondingly bedetermined (block 215) from the flowing fluid specific gravity and basedensity by a fluid characteristic determiner 161 having a fluid densitycalculator 163. Mass flow can also be calculated from the flowing fluiddensity calculated by the fluid characteristic determiner 161 andvolumetric flow rate from the vortex meter 65.

Where the configuration selected for the differential pressure meter 89does not provide for pressure and temperature compensation (block 217),the density and mass flow calculation can be inaccurate. A signalconditioner 133 can determine density corrected for pressure andtemperature (block 219) from the static pressure of the differentialpressure meter 89 and ambient temperature of the independent ambienttemperature sensor 113 or ambient temperature sensor 111 of the thermalflow meter 97, if so configured. Correspondingly, the signal conditioner133 can receive the mass flow rate, a function of density and volumetricflow rate, and correct it for pressure and temperature. In eitherconfiguration, density and mass flow rate, along with volumetric flowrate from the flow meter, are output (block 221) to a fluidcharacteristic display 35 in a manner known and understood by thoseskilled in the art.

In an embodiment of the present invention the user can install a thermalflow meter 97 or similar device adjacent the vortex-shedding body 63. Ifso installed (block 223), a mass flow meter can be used to verify thedensity and mass flow rate calculated from the differential pressuremeter flow rate signal. The mass flow meter is typically in the form ofa thermal flow meter 97 which measures a thermal energy change (block225) proportional to the mass of fluid 41 interfacing with a thermalflow detector 149, and outputs a signal indicative of mass flow rateindependent of density. The mass flow rate, which is not fluid-densitydependent, can be determined (block 227) directly from the mass flowmeter 97. A verifier 171 having its own fluid density calculator 173 candetermine a verification density (block 229) from the mass flow ratesignal of the thermal flow meter 97 in conjunction with the volumetricflow rate signal from the vortex meter 65. The verifier 171, also havinga comparator 175, can compare (block 231) the pressure and temperaturecompensated density signal from either a fluid characteristic determiner161 or signal conditioner 133, depending upon the selectedconfiguration, with the density signal from the fluid density calculator173 of the verifier 171 in order to verify reliability of the densitydetermined from the differential pressure meter flow rate signal. If thedensity signal is within a preselected tolerance (block 233), 4% forexample, the verifier 171 can output (block 235) a density verifiedsignal to the fluid characteristic display 35. The comparator 175 canalso compare (block 237) the pressure and temperature compensated massflow signal from the fluid characteristic determiner 161 or signalconditioner 133, also depending upon the selected configuration, withthe mass flow rate signal from the thermal flow meter 97 in order toverify reliability of the mass flow rate determined from thedifferential pressure meter flow rate signal is within preselectedtolerance (block 239), 4% for example. If so, the verifier can output(block 241) a mass flow rate verified signal to the fluid characteristicdisplay 35.

Another embodiment of the present invention, as perhaps best shown inFIG. 14, includes a method for measuring flowing fluid characteristicsin a pipeline using a process density meter having at least portionsthereof positioned within a fluid passageway of the pipeline. As withthe previous embodiments, the user predetermines a cross-sectional areaof a pipeline 31 having a flowing fluid 41 (block 251). The user alsoinstalls the vortex-shedding (bluff) body 63. The installation can beaccomplished by individually installing the vortex-shedding body 63within an existing piece of pipeline 31 (FIG. 4), or by installing thevortex-shedding body 63 within a housing 61 which can be positionedcoaxially between an upstream and a downstream section 43, 45, ofpipeline 31 (FIG. 2) or within a pipeline interior passageway 37 (FIG.3). The vortex-shedding body 63 is generally positioned across the innerdiameter 55 of the pipeline 31, transverse to the direction of a flowingfluid 41. The vortex-shedding body 63 causes the generation of VonKarman vortices which can be easily measured when fluid 41 is flowingwithin the pipeline 31.

The user also installs a vortex frequency detection device or sensor103, part of a vortex meter 65, either in the vortex-shedding body 63,the process density meter housing 61, or in a position on, in, or withinthe pipeline 31 in the vicinity of the vortex-shedding body 63. As fluid41 flows through the pipeline 31, the vortex-shedding body 63 causesvortices to be shed. The vortex meter 65 measures the frequency of VonKarman vortices (block 253) shed by the vortex-shedding body 63. Thevortex meter 65 then determines (block 255) volumetric flow rate of theflowing fluid 41 from the flowing fluid flow rate measured by the vortexfrequency sensor 103 and predetermined pipeline volumetric data,generally stored in a memory 101 of the vortex meter 65, and outputs arespective vortex meter flowing fluid flow rate signal for display. Thevortex meter 65 typically determines volumetric flow rate by calculatingthe product of the fluid flow rate as determined from the vortexfrequency sensor 103 and the cross-sectional area of the column of fluid41 flowing within the pipeline 31.

The user also installs a thermal flow meter 97 or similar deviceadjacent the vortex-shedding body 63. The thermal flow meter 97 includesthermal sensors to measure ambient temperature and a thermal energychange in the flowing fluid 41 (block 257) from which the thermal flowmeter can determine mass flow rate and output a signal indicative ofmass flow rate (block 259) independent of fluid density. Thoughindependent of density, the signal is nevertheless proportional to fluiddensity. A fluid characteristic determiner 161 having a fluid densitycalculator 163 can determine density (block 261) from the volumetricflow rate signal from the vortex meter 65, and non-density dependentmass flow rate signal from the thermal flow meter 97. All three fluidcharacteristic measurements, density, mass flow rate, and volumetricflow rate can be translated to the user through the fluid characteristicdisplay 35 or other methodology as known and understood by those skilledin the art.

In the drawings and specification, there have been disclosed embodimentsof the invention, and although specific terms are employed, the termsare used in a descriptive sense only and not for purposes of limitation.The invention has been described in considerable detail with specificreference to these illustrated embodiments. It will be apparent,however, that various modifications and changes can be made within thespirit and scope of the invention as described in the foregoingspecification and as defined in the attached claims.

1. A system for measuring fluid flow characteristics in a pipeline, thesystem comprising: a pipeline including a first fluid passageway havinga longitudinal axis to transport fluid therethrough; a process densitymeter having at least portions thereof positioned within the first fluidpassageway of the pipeline and including: a vortex-shedding bodypositioned within the first fluid passageway of the pipeline and having:an upstream surface positioned transverse to the longitudinal axisthereof, a plurality of downstream surfaces, a plurality of totalpressure inlet ports positioned in the upstream surface, a plurality ofstatic pressure inlet ports positioned in at least one of the downstreamsurfaces, a thermal sensor inlet port also positioned in the upstreamsurface, a thermal sensor outlet port also positioned in at least one ofthe downstream surfaces, a second fluid passageway extending between thethermal sensor inlet port and the thermal sensor outlet port andpositioned so that fluid flowing through the pipeline passestherethrough; a vortex meter positioned adjacent the vortex-sheddingbody including: a memory having pipeline volume data stored therein, avortex frequency sensor positioned adjacent the vortex-shedding body tosense the frequency of vortices shed by the vortex-shedding body tothereby produce a fluid flow rate signal responsive to the frequency ofvortices shed by the vortex-shedding body, and a volumetric flow ratecalculator positioned to receive the pipeline volume data stored in thememory and the flow rate signal from the vortex frequency sensor tocalculate a volumetric flow rate signal indicative of volumetric flowrate of fluid when flowing through the pipeline; a total pressuremanifold positioned in the vortex-shedding body and adjacent theupstream surface and having a plurality of total pressure inlet channelscoaxially aligned with the plurality of total pressure inlet ports inthe upstream surface and a total pressure outlet channel in fluidcommunication with the plurality of total pressure inlet channels sothat a first portion of fluid when flowing through the pipeline passesinto and through each of the total pressure inlet ports and out of thetotal pressure outlet channel; a static pressure manifold positioned inthe vortex-shedding body and adjacent at least one of the downstreamsurfaces and having a plurality of static pressure inlet channelsaligned with the plurality of static pressure inlet ports in the atleast one of the downstream surfaces and a static pressure outletchannel so that a second portion of fluid when flowing through thepipeline passes into and through each of the static pressure inlet portsand out of the static pressure outlet channel; a differential pressuremeter positioned adjacent the vortex-shedding body and including a totalpressure inlet positioned to receive fluid flowing through the totalpressure outlet channel, a static pressure inlet positioned to receivefluid flowing through the static pressure outlet channel, and adifferential pressure converter positioned to receive fluid pressurefrom the total pressure inlet and the static pressure inlet and toproduce a differential pressure meter flow rate signal proportional todensity of fluid when flowing through the pipeline; a thermal flow meterpositioned to produce a first mass flow rate signal indicative of a massflow rate of fluid when flowing through the pipeline and including: athermal flow probe positioned within the second fluid passagewayextending between the thermal sensor inlet port and thermal sensoroutlet port in the vortex-shedding body, the thermal flow probe having:a thermal sensor inlet in fluid communication with the thermal sensorinlet port in the upstream surface of the vortex-shedding body to allowa third portion of fluid flowing through the second fluid passageway toenter the thermal flow probe, a thermal sensor outlet in fluidcommunication with the thermal sensor outlet port in the at least one ofthe downstream surfaces of the vortex-shedding body to allow the thirdportion of fluid to exit the thermal flow probe, a thermal probe channelextending between the thermal sensor inlet and the thermal sensor outletso that the third portion of fluid when flowing through the thermalsensor inlet port passes into and through the thermal sensor inlet andso that the third portion of fluid passing into and through the thermalsensor inlet passes out of the thermal sensor outlet and out of thethermal sensor outlet port, an ambient temperature sensor positionedwithin the thermal probe channel to detect ambient temperature of thethird portion of fluid flowing between the thermal sensor inlet andthermal sensor outlet, and a thermal flow detection sensor positionedwithin the thermal probe channel to sense an amount of thermal energyremoved by the third portion of fluid flowing between the thermal sensorinlet and the thermal sensor outlet; a thermal flow meter mass flowsignal calculator responsive to the ambient temperature sensor and thethermal flow detection sensor to calculate the first mass flow ratesignal; a fluid characteristic determiner positioned in communicationwith the vortex meter, the differential pressure meter, and the thermalflow meter to process sensed signals therefrom, the fluid characteristicdeterminer including a first fluid density calculator responsive to thevolumetric flow rate signal received from the vortex meter and thedifferential pressure meter flow rate signal received from thedifferential pressure meter and positioned to calculate a first densitysignal indicative of flowing fluid density, and a fluid mass flow ratecalculator responsive to the volumetric flow rate received from thevortex meter and the differential pressure meter flow rate signalreceived from the differential pressure meter and positioned tocalculate a second mass flow rate signal indicative of flowing fluidmass flow rate; and a fluid characteristic display positioned externalto the first fluid passageway of the pipeline, in communication with theprocess density meter, and positioned to receive the volumetric flowrate signal, the first density signal, and the second mass flow ratesignal from the process density meter to display volumetric flow rate,flowing fluid density, and mass flow rate of the flowing fluid to a userthereof.
 2. A system as defined in claim 1, wherein the process densitymeter further includes a verifier responsive to the first density signaland the second mass flow rate signal from the fluid characteristicdeterminer to verify the accuracy of the first density signal and thesecond mass flow rate signal from the fluid characteristic determiner,the verifier including: a second fluid density calculator responsive tothe first mass flow rate signal from the thermal flow meter and thevolumetric flow rate signal from the vortex meter to calculate a seconddensity signal; and a comparator responsive to the second mass flow ratesignal and the first density signal from the fluid characteristicdeterminer and positioned to receive the first mass flow rate signalfrom the thermal flow meter, the volumetric flow rate from the vortexmeter, and the second density signal from the second fluid densitycalculator to compare the second mass flow rate signal from the fluidcharacteristic determiner with the sensed first mass flow rate signalfrom the thermal flow meter and to compare the first density signal fromthe fluid characteristic determiner with the second density signal fromthe second fluid density calculator to verify reliability of both thesecond mass flow rate signal and the first density signal from the fluidcharacteristic determiner to output a first verification signalindicating verified mass flow rate from the fluid characteristicdeterminer and a second verification signal indicating verified densityto thereby determine the accuracy of the second mass flow rate signaland the first density signal from the fluid characteristic determiner.3. A system as defined in claim 1, wherein the differential pressuremeter comprises an averaging pitot tube meter, and wherein thedifferential pressure converter of the differential pressure meterproduces a density dependent volumetric flow rate proportional to thequotient of a true flow rate divided by the square root of the ratio ofa base specific gravity and a true specific gravity.
 4. A system asdefined in claim 1, wherein the process density meter includes a signalconditioner responsive to the first density signal and the second massflow rate from the fluid characteristic determiner and positioned toreceive a temperature signal from the ambient temperature sensor of thethermal flow meter and a static pressure signal from the differentialpressure meter to condition the first density signal to form atemperature and pressure compensated first density signal and tocondition the second mass flow rate signal from the fluid mass flow ratecalculator to form a temperature and pressure compensated second massflow rate signal.
 5. A system as defined in claim 4, wherein the processdensity meter further includes a verifier responsive to the firstdensity signal and second mass flow rate signal from the signalconditioner to verify the accuracy of the first density signal andsecond mass flow rate signal from the signal conditioner, the verifierincluding: a second fluid density calculator responsive to the firstmass flow rate signal from the thermal flow meter and volumetric flowrate signal from the vortex meter to calculate a second density signal;and a comparator responsive to the second mass flow rate signal and thefirst density signal from the signal conditioner and positioned toreceive the first mass flow rate signal from the thermal flow meter, thevolumetric flow rate from the vortex meter, and the second densitysignal from the second fluid density calculator to compare the secondmass flow rate signal from the signal conditioner with the sensed firstmass flow rate signal from the thermal flow meter and to compare thefirst density signal from the signal conditioner with the second densitysignal from the second fluid density calculator to verify reliability ofboth the second mass flow rate signal and the first density signal fromthe signal conditioner to output a first verification signal indicatingverified mass flow rate and a second verification signal indicatingverified density from the signal conditioner to thereby determine theaccuracy of the second mass flow rate signal and the first densitysignal from the signal conditioner.
 6. A system as defined in claim 1,wherein the first fluid passageway of the pipeline has a predeterminedinner diameter, and wherein the process density meter further includes aprocess density meter housing including a first end, a second end, and athird fluid passageway extending therebetween and having an outerdiameter substantially the same as the predetermined inner diameter ofthe pipeline and in fluid communication with flowing fluid to supportthe vortex-shedding body of the vortex meter within the flowing fluid ofthe pipeline.
 7. A system as defined in claim 1, wherein the thermalflow meter mass flow signal calculator produces at least one of avoltage and a current required to maintain a constant temperaturedifferential between the ambient temperature sensor and the thermal flowdetection sensor.
 8. A system for measuring fluid flow characteristicsin a pipeline, the system comprising: a pipeline including a first fluidpassageway having a longitudinal axis to transport fluid therethrough; aprocess density meter having at least portions thereof positioned withinthe first fluid passageway of the pipeline and including: avortex-shedding body positioned within the first fluid passageway of thepipeline and having: an upstream surface positioned transverse to thelongitudinal axis thereof, a plurality of downstream surfaces, aplurality of total pressure inlet ports positioned in the upstreamsurface, and a plurality of static pressure inlet ports positioned in atleast one of the downstream surfaces; a vortex meter positioned adjacentthe vortex-shedding body including: a memory having pipeline volume datastored therein, a vortex frequency sensor positioned to sense thefrequency of vortices shed by the vortex-shedding body to therebyproduce a fluid flow rate signal responsive to the frequency of vorticesshed by the vortex-shedding body, and a volumetric flow rate calculatorpositioned to receive the pipeline volume data stored in the memory andthe flow rate signal from the vortex frequency sensor to calculate avolumetric flow rate signal indicative of volumetric flow rate of fluidwhen flowing through the pipeline; a total pressure manifold positionedin the vortex-shedding body and adjacent the upstream surface and havinga plurality of total pressure inlet channels coaxially aligned with theplurality of total pressure inlet ports in the upstream surface and atotal pressure outlet channel in fluid communication with the pluralityof total pressure inlet channels so that a first portion of fluid whenflowing through the pipeline passes into and through each of the totalpressure inlet ports and out of the total pressure outlet channel; astatic pressure manifold positioned in the vortex-shedding body andadjacent at least one of the downstream surfaces and having a pluralityof static pressure inlet channels aligned with the plurality of staticpressure inlet ports in the at least one of the downstream surfaces anda static pressure outlet channel so that a second portion of fluid whenflowing through the pipeline passes into and through each of the staticpressure inlet ports and out of the static pressure outlet channel; adifferential pressure meter positioned adjacent the vortex-shedding bodyand including a total pressure inlet positioned to receive fluid flowingthrough the total pressure outlet channel, a static pressure inletpositioned to receive fluid flowing through the static pressure outletchannel, and a differential pressure converter positioned to receivefluid pressure from the total pressure inlet and the static pressureinlet and to produce a differential pressure meter flow rate signalproportional to density of fluid when flowing through the pipeline; anda fluid characteristic determiner positioned in communication with thevortex meter, the differential pressure meter and the thermal flowmeter, to process sensed signals therefrom, the fluid characteristicdeterminer including a first fluid density calculator responsive to thevolumetric flow rate signal received from the vortex meter and thedifferential pressure meter flow rate signal received from thedifferential pressure meter and positioned to calculate a first densitysignal indicative of flowing fluid density and a fluid mass flow ratecalculator to calculate a first mass flow rate signal indicative offlowing fluid mass flow rate.
 9. A system as defined in claim 8, whereinthe process density meter further comprises a thermal flow meterpositioned to produce a second mass flow rate signal indicative of amass flow rate of fluid when flowing through the pipeline and including:a plurality of thermal sensors positioned adjacent the vortex-sheddingbody to provide thermal energy and to sense temperature of a thirdportion of fluid when flowing through the pipeline; and a thermal flowmeter mass flow signal calculator positioned adjacent thevortex-shedding body and responsive to the plurality of thermal sensorsto calculate the second mass flow rate signal.
 10. A system as definedin claim 9, wherein the process density meter further includes averifier responsive to the first density signal and the first mass flowrate signal from the fluid characteristic determiner to verify accuracyof the first flowing fluid density signal and the first mass flow ratesignal from the fluid characteristic determiner, the verifier including:a second fluid density calculator responsive to the second mass flowrate signal from the thermal flow meter and the volumetric flow ratesignal from the vortex meter to calculate a second density signal; and acomparator responsive to the first mass flow rate signal and the firstdensity signal from the fluid characteristic determiner and positionedto receive the second mass flow rate signal from the thermal flow meter,the volumetric flow rate from the vortex meter, and the second densitysignal from the second fluid density calculator to compare the firstmass flow rate signal from the fluid characteristic determiner with thesecond mass flow rate signal from the thermal flow meter and to comparethe first density signal from the fluid characteristic determiner withthe second density signal from the second fluid density calculator toverify reliability of both the first mass flow rate signal and the firstdensity signal from the fluid characteristic determiner to output afirst verification signal indicating verified mass flow rate from thefluid characteristic determiner and a second verification signalindicating verified density to thereby determine the accuracy of thefirst mass flow rate signal and the first density signal from the fluidcharacteristic determiner.
 11. A system as defined in claim 9, whereinthe process density meter further includes a signal conditionerresponsive to the first density signal and the first mass flow ratesignal from the fluid characteristic determiner and positioned toreceive temperature from the ambient temperature sensor of the thermalflow meter and a static pressure signal from the differential pressuremeter to condition the first density signal to form a temperature andpressure compensated first density signal and to condition the firstmass flow rate signal from the fluid mass flow rate calculator to form atemperature and pressure compensated first mass flow rate signal.
 12. Aprocess density meter as defined in claim 9, wherein the thermal flowmeter further includes a thermal flow probe to house a plurality ofthermal sensors and positioned adjacent the vortex-shedding body, thethermal flow probe having: a thermal sensor inlet positionedsubstantially parallel to the longitudinal axis of the pipeline and influid communication with the first fluid passageway of the pipeline toallow a third portion of fluid flowing through the first fluidpassageway to enter the thermal flow probe; a thermal sensor outletpositioned substantially parallel to the longitudinal axis of the firstfluid passageway of the pipeline to allow the third portion of fluid toexit the thermal flow probe; and a thermal probe channel extendingbetween the thermal sensor inlet and the thermal sensor outlet so thatthe third portion of fluid when flowing through the first fluidpassageway of the pipeline passes into and through the thermal sensorinlet, and so that the third portion of fluid passing into and throughthe thermal sensor inlet passes out of the thermal sensor outlet.
 13. Asystem as defined in claim 12, wherein the plurality of thermal sensorsinclude: an ambient temperature sensor positioned within the thermalprobe channel to detect ambient temperature of the third portion offluid flowing between the thermal sensor inlet and thermal sensoroutlet; and a thermal flow detection sensor positioned within thethermal probe channel to sense an amount of thermal energy removed bythe third portion of fluid flowing between the thermal sensor inlet andthe thermal sensor outlet.
 14. A system as defined in claim 29, whereinthe vortex-shedding body has a thermal sensor inlet port positioned inthe upstream surface, a thermal sensor outlet port positioned in atleast one of the downstream surfaces, and a second fluid passagewayextending between the thermal sensor inlet port and the thermal sensoroutlet port and positioned so that a third portion of fluid flowingthrough the first fluid passageway of the pipeline passes therethrough.15. A system as defined in claim 14, wherein the thermal flow meterfurther includes a thermal flow probe to house a plurality of thermalsensors and positioned within the second passageway extending betweenthe thermal sensor inlet port and thermal sensor outlet port in thevortex-shedding body, the thermal flow probe having: a thermal sensorinlet in fluid communication with the thermal sensor inlet port in theupstream surface of the vortex-shedding body to allow the third portionof fluid flowing through the second fluid passageway to enter thethermal flow probe; a thermal sensor outlet in fluid communication withthe thermal sensor outlet port in the at least one of the downstreamsurfaces of the vortex-shedding body to allow the third portion of fluidto exit the thermal flow probe; and a thermal probe channel extendingbetween the thermal sensor inlet and the thermal sensor outlet so thatthe third portion of fluid when flowing through the thermal sensor inletport passes into and through the thermal sensor inlet, and so that thethird portion of fluid passing into and through the thermal sensor inletpasses out of the thermal sensor outlet and out of the thermal sensoroutlet port.
 16. A system as defined in claim 8, wherein thedifferential pressure meter comprises an averaging pitot tube meter, andwherein the differential pressure converter of the differential pressuremeter produces a density dependent volumetric flow rate proportional tothe quotient of a true flow rate divided by the square root of the ratioof a base specific gravity and a true specific gravity.
 17. A system asdefined in claim 8, wherein the first fluid passageway of the pipelinehas a predetermined inner diameter, and wherein the process densitymeter further includes a process density meter housing including a firstend, a second end, and a third fluid passageway extending therebetweenand having an outer diameter substantially the same as the predeterminedinner diameter of the pipeline and in fluid communication with flowingfluid to support the vortex-shedding body of the vortex meter within theflowing fluid of the pipeline;
 18. A system as defined in claim 8,wherein the pipeline has an upstream and a downstream section, whereinthe first fluid passageway of the pipeline has a predetermined innerdiameter, and wherein the process density meter further includes aprocess density meter housing adapted to connect to the upstream anddownstream sections of the pipeline and including a first end, a secondend, and a third fluid passageway extending therebetween and having aninner diameter substantially the same as the predetermined innerdiameter of the pipeline and in fluid communication with flowing fluidto support the vortex-shedding body of the vortex meter within theflowing fluid of the pipeline.
 19. A system as defined in claim 8,wherein the vortex-shedding body is adapted to connect to the pipelineon opposite sides within the first fluid passageway.
 20. A system asdefined in claim 9, wherein the third portion of fluid is obstructedwhen flowing through the thermal sensors of the thermal flow meter, andwherein the mass flow signal calculator of the thermal flow meterfurther includes a thermal mass flow signal compensator to compensatefor an error induced by the obstructed flow.
 21. A system as defined inclaim 8, further comprising a fluid characteristic display positionedexternal to the first fluid passageway of the pipeline, in communicationwith the process density meter, and positioned to receive the volumetricflow rate signal, the first fluid density signal, and the first massflow rate signal from the process density meter to display volumetricflow rate, density, and mass flow rate of the flowing fluid to the userthereof.
 22. A process density meter for measuring fluid flowcharacteristics in a pipeline including a first fluid passageway havinga longitudinal axis to transport fluid therethrough, and having at leastportions thereof positioned within the first fluid passageway of thepipeline, the process density meter comprising: a vortex-shedding bodypositioned within the first fluid passageway of the pipeline and having:an upstream surface positioned transverse to the longitudinal axisthereof, at least one downstream surface, a plurality of total pressureinlet ports positioned in the upstream surface, and a plurality ofstatic pressure inlet ports positioned in the at least one downstreamsurface; a vortex meter positioned adjacent the vortex-shedding bodyincluding: a memory having pipeline volume data stored therein, a vortexfrequency sensor positioned to sense the frequency of vortices shed bythe vortex-shedding body to thereby produce a fluid flow rate signalresponsive to the frequency of vortices shed by the vortex-sheddingbody, and a volumetric flow rate calculator positioned to receive thepipeline volume data stored in the memory and flow rate signal from thevortex frequency sensor to calculate a volumetric flow rate signalindicative of volumetric flow rate of fluid when flowing through thepipeline; a total pressure manifold positioned in the vortex-sheddingbody and adjacent the upstream surface and having a plurality of totalpressure inlet channels coaxially aligned with the plurality of totalpressure inlet ports in the upstream surface and a total pressure outletchannel in fluid communication with the plurality of total pressureinlet channels so that a first portion of fluid when flowing through thepipeline passes into and through each of the total pressure inlet portsand out of the total pressure outlet channel; a static pressure manifoldpositioned in the vortex-shedding body and adjacent the at least onedownstream surface and having a plurality of static pressure inletchannels aligned with the plurality of static pressure inlet ports inthe at least one downstream surface and a static pressure outlet channelso that a second portion of fluid when flowing through the pipelinepasses into and through each of the static pressure inlet ports and outof the static pressure outlet channel; a differential pressure meterpositioned adjacent the vortex-shedding body and including a totalpressure inlet positioned to receive fluid flowing through the totalpressure outlet channel, a static pressure inlet positioned to receivefluid flowing through the static pressure outlet channel, and adifferential pressure converter positioned to receive fluid pressurefrom the total pressure inlet and the static pressure inlet and toproduce a differential pressure meter flow rate signal proportional todensity of fluid when flowing through the pipeline; and a fluidcharacteristic determiner positioned in communication with the vortexmeter and the differential pressure meter to process sensed signalstherefrom, the fluid characteristic determiner including a first fluiddensity calculator responsive to the volumetric flow rate signalreceived from the vortex meter and the differential pressure meter flowrate signal received from the differential pressure meter and positionedto calculate a first density signal indicative of flowing fluid density,and fluid mass flow rate calculator responsive to the volumetric flowrate signal received from the vortex meter and the differential pressuremeter flow rate signal received from the differential pressure meter andpositioned to calculate a first mass flow rate signal indicative offlowing fluid mass flow rate.
 23. A process density meter as defined inclaim 22, wherein the process density meter further includes an ambienttemperature sensor positioned within the first fluid passageway of thepipeline to detect an ambient temperature of a third portion of fluidflowing through the pipeline and produce an ambient temperature signal.24. A process density meter as defined in claim 23, wherein thedifferential pressure converter is also positioned to receive theambient temperature signal from the ambient temperature sensor, whereinthe differential pressure meter flow rate signal is proportional totemperature and pressure compensated density of the fluid when flowingthrough the pipeline, and wherein the density signal and mass flow ratesignal from the fluid characteristic determiner are both pressure andtemperature compensated.
 25. A process density meter as defined in claim23, wherein the process density meter further includes a signalconditioner responsive to the density signal and first mass flow ratesignal from the fluid characteristic determiner and positioned toreceive the ambient temperature signal from the ambient temperaturesensor and a static pressure signal from the differential pressure meterto condition the density signal from the first fluid characteristicdeterminer to form a temperature and pressure compensated first densitysignal and to condition the first mass flow rate signal from the fluidmass flow rate calculator to form a temperature and pressure compensatedmass flow rate signal.
 26. A process density meter as defined in claim22, wherein the differential pressure meter comprises an averaging pitottube meter, and wherein the differential pressure converter of thedifferential pressure meter produces a density dependent volumetric flowrate proportional to the quotient of a true flow rate divided by thesquare root of the ratio of a base specific gravity and a true specificgravity.
 27. A process density meter as defined in claim 22, wherein thefirst fluid passageway of the pipeline has a predetermined innerdiameter, and wherein the process density meter further includes aprocess density meter housing including a first end, a second end, and asecond fluid passageway extending therebetween and having an outerdiameter substantially the same as the predetermined inner diameter ofthe pipeline and in fluid communication with flowing fluid to supportthe vortex-shedding body of the vortex meter within the flowing fluid ofthe pipeline.
 28. A process density meter as defined in claim 22,wherein the pipeline has an upstream and a downstream section, whereinthe first fluid passageway of the pipeline has a predetermined innerdiameter, and wherein the process density meter further includes aprocess density meter housing adapted to connect to the upstream anddownstream sections of the pipeline and including a first end, a secondend, and a second fluid passageway extending therebetween and having aninner diameter substantially the same as the predetermined innerdiameter of the pipeline and in fluid communication with flowing fluidto support the vortex-shedding body of the vortex meter within theflowing fluid of the pipeline.
 29. A process density meter as defined inclaim 22, wherein the vortex-shedding body is adapted to connect to thepipeline on opposite sides within the first fluid passageway.
 30. Aprocess density meter as defined in claim 22, further comprising a fluidcharacteristic display positioned external to the first fluid passagewayof the pipeline, in communication with the vortex meter and the fluidcharacteristic determiner, and positioned to receive the volumetric flowrate signal from the vortex meter, and the fluid density signal and massflow rate signal from the fluid characteristic determiner to displayvolumetric flow rate, density, and mass flow rate of the flowing fluid,to a user thereof.
 31. A process density meter for measuring fluid flowcharacteristics in a pipeline including a first fluid passageway havinga longitudinal axis to transport fluid therethrough, and having at leastportions thereof positioned within the first fluid passageway of thepipeline, the process density meter comprising: a vortex-shedding bodypositioned within the first fluid passageway of the pipeline and having:an upstream surface positioned transverse to the longitudinal axisthereof, and a plurality of downstream surfaces; a vortex meterpositioned adjacent the vortex-shedding body including: a memory havingpipeline volume data stored therein, a vortex frequency sensorpositioned to sense the frequency of vortices shed by thevortex-shedding body to thereby produce a fluid flow rate signalresponsive to the frequency of vortices shed by the vortex-sheddingbody, and a volumetric flow rate calculator positioned to receive thepipeline volume data stored in the memory and the flow rate signal fromthe vortex frequency sensor to calculate a volumetric flow rate signalindicative of volumetric flow rate of fluid when flowing through thepipeline; a thermal flow meter positioned to produce a mass flow ratesignal indicative of a mass flow rate of fluid when flowing through thefirst fluid passageway of the pipeline and including: a plurality ofthermal sensors positioned adjacent the vortex-shedding body to providethermal energy and to sense temperature of a portion of fluid whenflowing through the first fluid passageway of the pipeline; and athermal flow meter mass flow signal calculator responsive to theplurality of thermal sensors and positioned to produce the mass flowrate signal; and a fluid characteristic determiner positioned incommunication with the vortex meter and the thermal flow meter toprocess sensed signals therefrom, the fluid characteristic determinerincluding a first fluid density calculator responsive to the volumetricflow rate signal received from the vortex meter and the mass flow ratesignal received from the thermal flow meter, and positioned to calculatea density signal indicative of flowing fluid density.
 32. A processdensity meter as defined in claim 31, wherein the thermal flow meterfurther includes a thermal flow probe to house a plurality of thermalsensors and positioned adjacent to the vortex-shedding body, the thermalflow probe having: a thermal sensor inlet positioned substantiallyparallel to the longitudinal axis of the pipeline and in fluidcommunication with the first fluid passageway of the pipeline to allowthe first portion of fluid flowing through the fluid passageway to enterthe thermal flow probe; a thermal sensor outlet positioned substantiallyparallel to the longitudinal axis of the pipeline to allow the portionof fluid to exit the thermal flow probe; and a thermal probe channelextending between the thermal sensor inlet and the thermal sensor outletso that the first portion of fluid when flowing through the pipelinepasses into and through the thermal sensor inlet and so that the portionof fluid passing into and through the thermal sensor inlet passes out ofthe thermal sensor outlet.
 33. A process density meter as defined inclaim 32, wherein the plurality of thermal sensors include an ambienttemperature sensor positioned within the thermal probe channel to detectambient temperature of the portion of fluid flowing between the thermalsensor inlet and thermal sensor outlet and a thermal flow detectionsensor positioned within the thermal probe channel to sense an amount ofthermal energy removed by the portion of fluid flowing between thethermal sensor inlet and the thermal sensor outlet.
 34. A processdensity meter as defined in claim 32, wherein the vortex-shedding bodyhas: a thermal sensor inlet port positioned in the upstream surface, athermal sensor outlet port positioned in at least one of the downstreamsurfaces, and a second passageway extending between the thermal sensorinlet port and the thermal sensor outlet port positioned so that theportion of fluid flowing fluid through the pipeline passes therethrough.35. A process density meter as defined in claim 34, wherein the thermalflow probe is positioned within the second passageway extending betweenthe thermal sensor inlet port and thermal sensor outlet port in thevortex-shedding body.
 36. A process density meter as defined in claim35, wherein: the thermal sensor inlet of the thermal flow probe is influid communication with the thermal sensor inlet port in the upstreamsurface of the vortex-shedding body to allow a first portion of fluidflowing through the second fluid passageway to enter the thermal flowprobe; the thermal sensor outlet of the thermal probe is in fluidcommunication with the thermal sensor outlet port in the at least one ofthe downstream surfaces of the vortex-shedding body to allow the firstportion of fluid to exit the thermal flow probe; and the first portionof fluid when flowing through the thermal sensor inlet port passes intoand through the thermal sensor inlet, passes out of the thermal sensoroutlet, and passes out of the thermal sensor outlet port.
 37. A processdensity meter as defined in claim 31, wherein the portion of fluid isobstructed when flowing through the thermal sensors of the thermal flowmeter, and wherein the thermal flow meter mass flow signal calculator ofthe thermal flow meter further includes a thermal mass flow signalcompensator to compensate for an error induced by the obstructed flow.38. A process density meter as defined in claim 31, wherein the firstfluid passageway of the pipeline has a predetermined inner diameter,wherein the process density meter further includes a process densitymeter housing including a first end, a second end, and a second fluidpassageway extending therebetween and having an outer diametersubstantially the same as the predetermined inner diameter of thepipeline and in fluid communication with flowing fluid to support thevortex-shedding body of the vortex meter within the flowing fluid of thepipeline;
 39. A process density meter as defined in claim 31, whereinthe pipeline has an upstream and a downstream section, wherein the firstfluid passageway of the pipeline has a predetermined inner diameter, andwherein the process density meter further includes a process densitymeter housing adapted to connect to the upstream and downstream sectionsof the pipeline and including a first end, a second end, and a secondfluid passageway extending therebetween and having an inner diametersubstantially the same as the predetermined inner diameter of thepipeline and in fluid communication with flowing fluid to support thevortex-shedding body of the vortex meter within the flowing fluid of thepipeline.
 40. A process density meter as defined in claim 31, whereinthe vortex-shedding body is adapted to connect to the pipeline onopposite sides within the first fluid passageway.
 41. A process densitymeter as defined in claim 31, further comprising a fluid characteristicdisplay positioned external to the first fluid passageway of thepipeline, in communication with the vortex meter and the fluidcharacteristic determiner, and positioned to receive the volumetric flowrate signal from the vortex meter, the mass flow rate from the thermalflow meter, and the fluid density signal from the fluid characteristicdeterminer to display volumetric flow rate, density, and mass flow rateof the flowing fluid, to a user thereof.
 42. (Currently owned) A methodfor measuring flowing fluid characteristics in a pipeline using aprocess density meter having at least portions thereof positioned withina fluid passageway of the pipeline, the method comprising the steps of:measuring a vortex frequency shedding rate of a vortex shedding bodywith a vortex meter to determine both a fluid flow rate and volumetricflow rate; measuring differential pressure formed by the vortex-sheddingbody with a differential pressure meter to determine a density andspecific gravity dependent fluid flow rate; determining the specificgravity of the flowing fluid from the volumetric flow rate and thedifferential pressure meter flow rate; determining density from thespecific gravity determined from the volumetric flow rate and thedifferential pressure meter flow rate; and displaying density andvolumetric flow rate to a user thereof on a fluid characteristic displaypositioned to receive density and volumetric flow rate.
 43. A method ofclaim 42, further comprising the steps of: measuring static pressure andambient temperature of the flowing fluid; determining pressure andtemperature compensated density by compensating the density determinedfrom signals from the vortex meter and differential pressure meter witha static pressure and an ambient temperature of the flowing fluid;determining mass flow rate from the pressure and temperature compensateddensity and volumetric flow rate; and displaying pressure andtemperature compensated density, mass flow rate and volumetric flow rateto a user thereof on a fluid characteristic display positioned toreceive pressure and temperature compensated density, volumetric flowrate, and mass flow rate.
 44. A method of claim 43, further comprisingthe steps of: measuring mass flow rate using a non-density dependentmass flow rate meter; determining density from the non-density dependentmass flow rate and the volumetric flow rate of the vortex meter; andverifying accuracy of the pressure and temperature compensated densityand verifying the accuracy of the mass flow rate determined from thepressure and temperature compensated density by comparing the mass flowrate determined from the pressure and temperature compensated densitywith the mass flow rate measured by the non-density dependent mass flowrate meter and by comparing the pressure and temperature compensateddensity with the density determined from the mass flow rate measured bythe non-density dependent mass flow rate meter.
 45. A method formeasuring flowing fluid characteristics in a pipeline using a processdensity meter having at least portions thereof positioned within a fluidpassageway of the pipeline, the method including the steps of: measuringa vortex frequency shedding rate with a vortex meter to determine both afluid flow rate and volumetric flow rate; measuring mass flow rate usinga non-density dependent mass flow rate meter; determining density fromthe non-density dependent mass flow rate meter and volumetric flow ratefrom the vortex meter; and displaying density, mass flow rate andvolumetric flow rate to a user thereof on a fluid characteristic displaypositioned to receive density, volumetric flow rate, and mass flow rate.46. A system for measuring fluid flow characteristics in a pipeline, thesystem comprising: a pipeline including a first fluid passageway havinga longitudinal axis to transport fluid therethrough; a process densitymeter having at least portions thereof positioned within the first fluidpassageway of the pipeline and including: a vortex-shedding bodypositioned within the first fluid passageway of the pipeline and having:an upstream surface positioned transverse to the longitudinal axisthereof, a plurality of downstream surfaces, a thermal sensor inlet portalso positioned in the upstream surface, a thermal sensor outlet portalso positioned in at least one of the downstream surfaces, and a secondfluid passageway extending between the thermal sensor inlet port and thethermal sensor outlet port and positioned so that fluid flowing throughthe pipeline passes therethrough; a vortex meter positioned adjacent thevortex-shedding body including: a memory having pipeline volume datastored therein, a vortex frequency sensor positioned adjacent thevortex-shedding body to sense the frequency of vortices shed by thevortex-shedding body to thereby produce a fluid flow rate signalresponsive to the frequency of vortices shed by the vortex-sheddingbody, and a volumetric flow rate calculator positioned to receive thepipeline volume data stored in the memory and the flow rate signal fromthe vortex frequency sensor to calculate a volumetric flow rate signalindicative of volumetric flow rate of fluid when flowing through thepipeline; a thermal flow meter positioned to produce a mass flow ratesignal indicative of a mass flow rate of fluid when flowing through thepipeline and including: a thermal flow probe positioned within thesecond fluid passageway extending between the thermal sensor inlet portand thermal sensor outlet port in the vortex-shedding body to house aplurality of thermal sensors, the plurality of thermal sensorspositioned to provide thermal energy and to sense temperature of aportion of fluid when flowing through the pipeline, and a thermal flowmeter mass flow signal calculator positioned adjacent thevortex-shedding body and responsive to the plurality of thermal sensorsto calculate the mass flow rate signal; and a fluid characteristicdeterminer positioned in communication with the vortex meter and thethermal flow meter to process sensed signals therefrom, the fluidcharacteristic determiner including a fluid density calculatorresponsive to the volumetric flow rate signal received from the vortexmeter and the mass flow rate signal received from the thermal flowmeter, and positioned to calculate a density signal indicative offlowing fluid density.
 47. A system as defined in claim 46, wherein thethermal flow probe further includes: a thermal sensor inlet in fluidcommunication with the thermal sensor inlet port in the upstream surfaceof the vortex-shedding body to allow the portion of fluid flowingthrough the second fluid passageway to enter the thermal flow probe; athermal sensor outlet in fluid communication with the thermal sensoroutlet port in the at least one of the downstream surfaces of thevortex-shedding body to allow the portion of fluid to exit the thermalflow probe; and a thermal probe channel extending between the thermalsensor inlet and the thermal sensor outlet so that the portion of fluidwhen flowing through the thermal sensor inlet port passes into andthrough the thermal sensor inlet and so that the portion of fluidpassing into and through the thermal sensor inlet passes out of thethermal sensor outlet and out of the thermal sensor outlet port.
 48. Asystem as defined in claim 46, wherein the plurality of thermal sensorsinclude an ambient temperature sensor positioned within the thermalprobe channel to detect ambient temperature of the portion of fluidflowing between the thermal sensor inlet and thermal sensor outlet, anda thermal flow detection sensor positioned within the thermal probechannel to sense an amount of thermal energy removed by the portion offluid flowing between the thermal sensor inlet and the thermal sensoroutlet.
 49. A system as defined in claim 46, wherein the portion offluid is obstructed when flowing through the thermal sensors of thethermal flow meter, and wherein the thermal flow meter mass flow signalcalculator of the thermal flow meter further includes a thermal massflow signal compensator to compensate for an error induced by theobstructed flow.
 50. A system as defined in claim 46, wherein theportion of fluid flowing through the pipeline is a first portion offluid; wherein the vortex-shedding body further includes: a plurality oftotal pressure inlet ports positioned in the upstream surface, and aplurality of static pressure inlet ports positioned in at least one ofthe downstream surfaces; and wherein the process density meter furtherincludes: a total pressure manifold positioned in the vortex-sheddingbody and adjacent the upstream surface and having a plurality of totalpressure inlet channels coaxially aligned with the plurality of totalpressure inlet ports in the upstream surface and a total pressure outletchannel in fluid communication with the plurality of total pressureinlet channels so that a second portion of fluid when flowing throughthe pipeline passes into and through each of the total pressure inletports and out of the total pressure outlet channel, a static pressuremanifold positioned in the vortex-shedding body and adjacent at leastone of the downstream surfaces and having a plurality of static pressureinlet channels aligned with the plurality of static pressure inlet portsin the at least one of the downstream surfaces and a static pressureoutlet channel so that a third portion of fluid when flowing through thepipeline passes into and through each of the static pressure inlet portsand out of the static pressure outlet channel, and a differentialpressure meter positioned adjacent the vortex-shedding body andincluding a total pressure inlet positioned to receive fluid flowingthrough the total pressure outlet channel, a static pressure inletpositioned to receive fluid flowing through the static pressure outletchannel, and a differential pressure converter positioned to receivefluid pressure from the total pressure inlet and the static pressureinlet and to produce a differential pressure meter flow rate signalproportional to density of fluid when flowing through the pipeline. 51.A system as defined in claim 50, wherein the differential pressure metercomprises an averaging pitot tube meter, and wherein the differentialpressure converter of the differential pressure meter produces a densitydependent volumetric flow rate proportional to the quotient of a trueflow rate divided by the square root of the ratio of a base specificgravity and a true specific gravity.
 52. A system as defined in claim50, wherein the process density meter includes a signal conditionerresponsive to the density signal from the fluid characteristicdeterminer and positioned to receive a temperature signal from theambient temperature sensor of the thermal flow meter and a staticpressure signal from the differential pressure meter to condition thefirst density signal to form a temperature and pressure compensateddensity signal.
 53. A computer readable medium that is readable by acomputer for measuring fluid flow characteristics in a pipeline, thecomputer readable medium comprising a set of instructions that, whenexecuted by the computer, cause the computer to perform the followingoperations: receiving a volumetric flow rate signal from a vortex meterpositioned adjacent a vortex shedding body, the volumetric flow ratesignal indicative of volumetric flow rate of fluid when flowing throughthe pipeline; receiving a differential pressure meter flow rate signalrepresenting a differential pressure across the vortex-shedding body,the differential pressure meter having a total pressure inlet portpositioned in the upstream surface of the vortex shedding body; andresponsive to the differential pressure meter flow rate signal and thevolumetric flow rate signal, determining a first determined density andspecific gravity dependent fluid flow rate.
 54. A computer readablemedium according to claim 53, further comprising a set of instructionsthat, when executed by the computer, cause the computer to perform thefollowing operations: compensating the first determined density with astatic pressure and an ambient temperature of the flowing fluid, tothereby determine a pressure and temperature compensated firstdetermined density; responsive to the pressure and temperaturecompensated first determined density and volumetric flow rate,determining a first mass flow rate; and displaying the first determineddensity, mass flow rate, and volumetric flow rate to a user thereof on afluid characteristic display.
 55. A computer readable medium accordingto claim 53, further comprising a set of instructions that, whenexecuted by the computer, cause the computer to perform the followingoperations: receiving a mass flow rate signal from a non-densitydependent mass flow rate meter, the mass flow rate signal indicating ameasured mass flow rate of the fluid; responsive to the non-densitydependent mass flow rate signal from the mass flow rate meter and thevolumetric flow rate signal from the vortex meter, determining a seconddetermined density of the fluid; and verifying accuracy of the firstdetermined density and verify the accuracy of the determined mass flowrate by comparing the determined mass flow rate with the measured massflow rate and by comparing the first determined density with the seconddetermined density.
 56. A computer readable medium that is readable by acomputer for measuring fluid flow characteristics in a pipeline, thecomputer readable medium comprising a set of instructions that, whenexecuted by the computer, cause the computer to perform the followingoperations: receiving a volumetric flow rate signal from a vortex meterpositioned adjacent a vortex shedding body, the volumetric flow ratesignal indicative of volumetric flow rate of fluid when flowing throughthe pipeline, receiving a mass flow rate signal from a non-densitydependent mass flow rate meter positioned adjacent the vortex sheddingbody, the mass flow rate signal indicating a measured mass flow rate ofthe fluid; responsive to the non-density dependent mass flow rate signalfrom the mass flow rate meter and the volumetric flow rate signal fromthe vortex meter, determining a density of the fluid; and displayingdensity, mass flow rate and volumetric flow rate to a user thereof on afluid characteristic display.